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Pregunta 1 Informe
Mouth part adapted for piercing and sucking is found in
Detalles de la respuesta
The mouthpart adapted for piercing and sucking is found in the mosquito. Mosquitoes have a specialized mouth structure called a proboscis. This proboscis is long and slender, allowing mosquitoes to puncture the skin of their hosts and suck blood. The proboscis is a complex structure that contains several needle-like parts that make the piercing and sucking process efficient and effective.
Pregunta 2 Informe
The distance between two successive crests of a water wave is 0.25m. If a particle on the surface of the water makes four complete vertical oscillations in one second. Calculate the speed of the wave.
Detalles de la respuesta
To calculate the speed of the wave, we need to understand some fundamental wave properties: **wavelength**, **frequency**, and **wave speed**.
1. **Wavelength (\( \lambda \))**: The wavelength is the distance between two successive crests of a wave. In this case, the wavelength is given as **0.25 meters**.
2. **Frequency (\( f \))**: Frequency is the number of complete oscillations or cycles that occur per second. It is given that a particle on the surface of the water makes **four complete vertical oscillations in one second**. So, the frequency is **4 Hz (hertz)**.
3. **Wave Speed (\( v \))**: The speed of a wave is calculated using the formula:
\( v = f \times \lambda \)
Where:
\( v \) is the wave speed,
\( f \) is the frequency, and
\( \lambda \) is the wavelength.
Substitute the given values into the formula:
\( v = 4 \text{ Hz} \times 0.25 \text{ m} \)
\( v = 1 \text{ m/s} \)
Therefore, the **speed of the wave** is 1 m/s.
Pregunta 3 Informe
The average translational kinetic energy of gas molecules depends on
Detalles de la respuesta
The average translational kinetic energy of gas molecules is directly related to the temperature of the gas. This relationship is based on the principles of kinetic molecular theory, which explains the behavior of gas molecules in terms of their motion.
Let's break this down simply:
1. Temperature and Kinetic Energy:
The average translational kinetic energy of gas molecules is given by the equation:
\( KE_{avg} = \frac{3}{2} k_B T \)
where \( KE_{avg} \) is the average translational kinetic energy, \( k_B \) is the Boltzmann constant, and \( T \) is the absolute temperature in Kelvin. This formula shows that the kinetic energy is directly proportional to the temperature.
2. What This Means:
As the temperature of a gas increases, the molecules move faster, which increases their translational kinetic energy. Conversely, as the temperature decreases, the molecules slow down, resulting in lower kinetic energy.
It is important to note that this relation is independent of the pressure and the number of moles of the gas. While pressure and the number of moles do affect the overall behavior of a gas, they do not directly influence the average translational kinetic energy of individual molecules.
Therefore, the correct explanation is that the average translational kinetic energy of gas molecules depends on temperature only.
Pregunta 4 Informe
Calculate the value of electric field intensity due to a charge of 4μC if the force due to the charge is 8N
Detalles de la respuesta
To calculate the electric field intensity due to a charge, we need to use the formula:
Electric Field Intensity (E) = Force (F) / Charge (q)
In this problem, we are given that the force (F) is 8 Newtons (N) and the charge (q) is 4 microcoulombs (μC). First, we need to convert the charge from microcoulombs to coulombs:
1 microcoulomb (μC) = 1 x 10-6 coulombs (C)
Therefore, 4 μC = 4 x 10-6 C.
Now we can use the formula to find the electric field intensity:
E = F / q
E = 8 N / (4 x 10-6 C)
E = 8 / 4 x 106
E = 2 x 106
Thus, the value of the electric field intensity is 2 x 106 N/C.
Pregunta 5 Informe
The formation of cilia and flagella in living cells is carried out with the help of
Detalles de la respuesta
The formation of cilia and flagella in living cells is primarily carried out with the help of **centrioles**.
Here's a simple explanation:
Centrioles are cylindrical structures made up of microtubules. They are found in eukaryotic cells and play a critical role in cell division and the organization of the cell's cytoskeleton. However, their role extends beyond this to the formation of the basal bodies which seed the growth of cilia and flagella.
Cilia and flagella are microscopic, hair-like structures that protrude from the surface of certain eukaryotic cells. They are primarily involved in movement. Cilia often work like tiny oars, moving fluid across the cell's surface or propelling single-celled organisms. Flagella are typically longer and move in a whip-like fashion to propel cells, such as sperm cells.
Here's how centrioles contribute to the formation of these structures:
1. **Basal Body Formation**: Each cilium or flagellum grows out from a structure known as a basal body. The basal body is derived from the centrioles. During this process, a centriole migrates to the cell's surface and acts as a nucleation site for the growth of microtubules, which in turn form the structural core of cilia and flagella.
2. **Microtubule Organization**: The centrioles help organize microtubules in a "9+2" arrangement, which is characteristic of cilia and flagella. This refers to nine pairs of microtubules forming a ring around two central microtubules, giving these structures both stability and flexibility for movement.
Thus, centrioles are crucial as they provide the groundwork for the formation and proper functioning of cilia and flagella. They ensure that these structures are assembled correctly and are able to carry out their roles in cell movement and fluid transport.
Pregunta 6 Informe
Calculate the depth of a swimming pool if the apparent depth is 10cm. ( Refractive index of water = 1.33 )
Detalles de la respuesta
To calculate the real depth of a swimming pool given the apparent depth, we can use the concept of refraction of light. When light passes from one medium to a denser medium, it bends towards the normal. This bending effect causes objects submerged in water to appear closer to the surface than they actually are. The formula to relate these depths is given by:
Real Depth = Apparent Depth × Refractive Index
Given the problem:
Using the formula:
Real Depth = 10 cm × 1.33
Calculating the above:
Therefore, the depth of the swimming pool is 13.3cm.
Pregunta 7 Informe
A monochromatic light is one that
Detalles de la respuesta
A monochromatic light is one that has a single wavelength or color. This means that it consists of light waves that all have the same frequency, resulting in a uniform appearance without any variation.
Pregunta 8 Informe
The equivalent capacitance of the capacitors in the circuit above
Detalles de la respuesta
apacitance in parallel = one at the top + one under = 2C
The two in the middle are in series = C2
The equivalent capacitance of the capacitors in the circuit above = C2 + 2C = 52 C
Pregunta 9 Informe
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called
Detalles de la respuesta
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called the friction force.
Let me explain each of the options to clarify why friction force is the correct answer:
In summary, friction force is the force that acts to oppose sliding between surfaces in contact and acts tangentially, making it the correct answer.
Pregunta 10 Informe
The process by which plants loss water to the atmosphere is
Detalles de la respuesta
The process by which plants lose water to the atmosphere is called transpiration.
Transpiration is a fundamental process in the life of a plant. During this process, water is absorbed by the roots from the soil and is then transported through the xylem vessels in the stem and leaves. Once in the leaves, water evaporates into the atmosphere from the surface of tiny pores known as stomata.
Here's a simple breakdown of how transpiration works:
Transpiration is crucial for a number of reasons:
Understanding transpiration is essential in fields like agriculture, where managing water resources efficiently can significantly impact plant growth and crop yield.
Pregunta 11 Informe
Detalles de la respuesta
In a series resonant circuit, the current flowing in the circuit is at its maximum. Let me explain why:
In a series resonant circuit, we have a resistor (R), inductor (L), and capacitor (C) connected in series with an AC source. At a particular frequency called the resonant frequency, these circuits exhibit some unique characteristics. This resonant frequency is determined by the values of the inductor and capacitor and is given by the formula:
f₀ = 1 / (2π√(LC))
At the resonant frequency:
Thus, in a series resonant circuit, when it is operating at its resonant frequency, the current flowing is at its maximum.
Pregunta 12 Informe
The stress experienced by a wire of diameter
Detalles de la respuesta
Stress is defined as the force applied per unit area. In the context of a wire being loaded by a weight, the weight acts as the force exerted, and the cross-sectional area of the wire is the area over which this force is distributed.
Force (F): This is given by the weight, which is y2 N.
Cross-sectional Area (A): For a wire with a diameter, the area can be calculated using the formula for the area of a circle: A = πr2, where r is the radius of the wire.
Given the diameter of the wire as yπ meters, the radius (r) is half of the diameter:
r = (yπ)/2
So, the area (A) is:
A = π[(yπ)/2]2
Simplifying the area:
A = π(y2π2/4)
A = y2π3/4
Stress (σ) is given by the formula:
σ = F/A
Substituting the given weight (force) and the calculated area:
σ = (y2) / (y2π3/4)
By simplifying the expression:
σ = (4y2) / (y2π3)
Cancel out y2 from numerator and denominator:
σ = 4/π2 Nm−2
Thus, the correct stress experienced by the wire is 4π Nm−2, as provided in one of the options. The explanation shows clearly how the force and area are used to derive the stress experienced by the wire.
Pregunta 13 Informe
A blacksmith heated a metal whose cubic expansivity is 3.9 x 10−6 K−1 . Calculate the area expansivity.
Detalles de la respuesta
To find the area expansivity of a metal when given its cubic expansivity, you should understand the relationship between linear, area, and cubic expansivity.
Cubic expansivity (\( \beta \)) is defined as the fractional change in volume per change in temperature, and is given by the formula:
\[ \Delta V = \beta V \Delta T \]
Area expansivity (\( \alpha_{A} \)) corresponds to the fractional change in area per change in temperature and can be derived from the linear expansivity (\( \alpha \)). The relationship between these expansivities is as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = 2 \times \text{Linear Expansivity (\( \alpha \))} \]
The cubic expansivity (\( \beta \)) is related to the linear expansivity by:
\[ \text{Cubic Expansivity (\( \beta \))} = 3 \times \text{Linear Expansivity (\( \alpha \))} \]
Thus, based on these relationships, we can express the area expansivity in terms of the cubic expansivity:
\(\text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times \text{Cubic Expansivity (\( \beta \))}
Given that the cubic expansivity \( \beta \) is \( 3.9 \times 10^{-6} \, \text{K}^{-1} \):
The area expansivity can be calculated as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times 3.9 \times 10^{-6} \, \text{K}^{-1} = 2.6 \times 10^{-6} \, \text{K}^{-1} \]
Therefore, the **correct answer** is **2.6 x 10^{-6} K^{-1}**.
Pregunta 14 Informe
If a charge ion goes through a combined electric field E and magnetic field B, the resultant emergent velocity of the ion is
Detalles de la respuesta
The resultant emergent velocity of a charged ion moving through combined electric and magnetic fields can be derived from the condition where the electric force equals the magnetic force. This gives us the formula for the velocity v:
q E = qvB
v = EB (q will cancel out)
NOTE: When both fields are present, for the ion to move without deflection, the electric force must equal the magnetic force.
Pregunta 15 Informe
A practical application of total internal reflection is found in
Detalles de la respuesta
A practical application of total internal reflection is found in fiber optics.
To understand this, let's break it down:
When light travels from one medium to another (such as from glass to air), it changes direction. This is known as refraction. However, there is a phenomenon called total internal reflection which occurs when light is traveling within a denser medium towards a less dense medium (like from glass to air) and hits the boundary at an angle greater than a certain critical angle. Instead of passing through, the light is completely reflected back into the denser medium.
Fiber optics technology makes use of this principle. In fiber optics, light is transmitted along the core of a thin glass or plastic fiber. The core is surrounded by another layer called the cladding. This cladding has a lower refractive index than the core, which facilitates total internal reflection. As a result, the light continuously reflects internally along the length of the fiber, allowing it to travel long distances with minimal loss.
This property is harnessed in various applications such as in high-speed telecommunication systems, medical equipment like endoscopes, and other technologies that require the transmission of data over long distances with high efficiency.
Pregunta 16 Informe
The fourth overtone of a closed pipes is 900Hz, its fundamental frequency is
Detalles de la respuesta
To solve this problem, let's first understand how sound works in a closed pipe. A closed pipe has one end closed and another end open. Sound waves inside such a pipe create standing waves, where nodes (points of no movement) and antinodes (points of maximum movement) are formed.
For a closed pipe, the fundamental frequency (also called the first harmonic) has one node at the closed end and one antinode at the open end. The wavelength is four times the length of the pipe.
The overtone sequence for a closed pipe includes only odd harmonics: 1st (fundamental), 3rd, 5th, 7th, etc. The nth overtone is the 2nth + 1 harmonic. The equation for the frequency of a harmonic in a closed pipe is:
f_n = n * f_1, where f_n is the frequency of the nth harmonic and f_1 is the fundamental frequency
In this case, the fourth overtone corresponds to the 9th harmonic because 2 * 4 + 1 = 9. Therefore, we have:
900 Hz = 9 * f_1
To find the fundamental frequency (f_1), we solve for f_1:
f_1 = 900 Hz / 9
f_1 = 100 Hz
Therefore, the fundamental frequency is 100 Hz.
Pregunta 17 Informe
An electron falls from an energy level of -5.44eV to another energy level, E. If the emitted photon is of wavelength 5.68 x 10−6 m, calculate the energy change. [ Plank's constant = 6.63 x 10−34 Js, emitted radiation speed = 3.0 x 108 ms−1 ]
Detalles de la respuesta
To find the energy change when an electron falls from one energy level to another, we need to calculate the energy of the emitted photon. This energy can be found using the formula:
E = hν or E = hc/λ
where:
Substitute these values into the equation:
E = (6.63 x 10-34 Js) * (3.0 x 108 ms-1) / (5.68 x 10-6 m)
First, calculate the numerator:
(6.63 x 10-34) * (3.0 x 108) = 1.989 x 10-25 J·m
Then, divide by the wavelength:
E = 1.989 x 10-25 J·m / 5.68 x 10-6 m = 3.5 x 10-20 J
Therefore, the energy change when the electron falls is approximately 3.5 x 10-20 J.
Checking the options provided, the closest value is 3.49 x 10-20 J.
Pregunta 18 Informe
A light ray passing from air into water at an angle of 30º from the normal in air would
Detalles de la respuesta
When light passes from one medium to another, such as from air to water, it bends or refracts. This phenomenon is described by Snell's Law, which states: n₁ * sin(θ₁) = n₂ * sin(θ₂), where:
The refractive index of air is approximately 1, and the refractive index of water is approximately 1.33. Given the angle of incidence in air is 30º:
Using Snell's Law:
1 * sin(30º) = 1.33 * sin(θ₂)
You will find:
sin(θ₂) = sin(30º) / 1.33
sin(θ₂) ≈ 0.5 / 1.33
sin(θ₂) ≈ 0.375
Now, solve for θ₂ by taking the inverse sine (arcsin):
θ₂ ≈ arcsin(0.375)
θ₂ ≈ 22.09º
Thus, when a light ray passes from air into water at an angle of 30º from the normal in air, it will make an angle less than 30º from the normal in water, approximately 22.09º. This is because the light ray bends toward the normal as it enters a denser medium (water).
Pregunta 19 Informe
When thermal energy in a solid is increased, the change in state is called
Detalles de la respuesta
When the thermal energy in a solid is increased, the solid particles gain energy and begin to vibrate more vigorously. As the temperature rises, these particles eventually have enough energy to overcome the forces holding them in their fixed positions. This leads to a change of state from a solid to a liquid. This process is known as melting.
To further understand this, imagine an ice cube. As it absorbs heat, it gains energy, and the ice (which is a solid) starts to turn into water (which is a liquid). This transition is what we refer to as melting.
Thus, the term that describes this change of state, when a solid is heated and turns into a liquid, is melting.
Pregunta 20 Informe
The energy in a moving car is an example of
Detalles de la respuesta
The energy in a moving car is an example of kinetic energy.
To explain simply, **energy** is the ability to do **work** or cause **change**. There are different forms of energy, and **kinetic energy** is one of them. It is defined as the energy possessed by an object due to its motion.
When a car is moving, it possesses **kinetic energy** because its components are in **motion**. This motion energy allows the car to do tasks, such as transporting people or goods from one place to another. The faster the car moves, the greater its **kinetic energy**, and thus it can make a larger impact or do more work.
In contrast, energy forms like **mechanical energy** is a combination of both kinetic and potential energy; **electrical energy** is associated with electrical charge movement, while **potential energy** is related to the position or condition of an object (like a car parked on a hill). Therefore, the specific type of energy from a moving car is **kinetic energy**.
Pregunta 21 Informe
Newton's law of cooling is valid only for a
Detalles de la respuesta
Newton's Law of Cooling states that the rate of heat loss of an object is directly proportional to the difference in temperature between the object and its surroundings, provided that this temperature difference is small.
Therefore, this law is only valid within a small temperature range.
Pregunta 22 Informe
One main feature of trees in the savanna habitat is the possession of
Detalles de la respuesta
The main feature of trees in the savanna habitat is the possession of thick, corky bark. The savanna is characterized by a distinct wet and dry season. During the dry season, fires are common as dry grasses and leaves become highly flammable. To adapt to this environmental condition, many trees in the savanna have developed a thick, corky bark which helps protect them against these frequent fires. This bark acts as an insulator, shielding the vital inner tissues of the tree from the heat of the flames. Additionally, this adaptation helps the trees retain moisture, which is crucial during the arid months when water is scarce.
Pregunta 23 Informe
A mass of gas at 40mmHg is heated from 298k to 348k at constant volume. Cal the pressure exerted by the gas.
Detalles de la respuesta
To determine the new pressure exerted by the gas when it is heated, we'll apply **Gay-Lussac's Law**. This law states that at constant volume, the pressure of a given amount of gas is directly proportional to its absolute temperature. Mathematically, it can be expressed as:
P1/T1 = P2/T2
Where:
By rearranging the formula to solve for the final pressure (P2), we get:
P2 = P1 * (T2/T1)
Now, insert the given values into the equation:
P2 = 40 mmHg * (348 K / 298 K)
Perform the calculations:
P2 = 40 mmHg * (348 / 298)
P2 = 40 mmHg * 1.1678
P2 = 46.71 mmHg
So, the new pressure exerted by the gas when it is heated from 298 K to 348 K at constant volume is 46.71 mmHg.
Pregunta 24 Informe
Use the diagram above to answer the question that follows
The diagram above is
Detalles de la respuesta
The diagram in the image represents the urinary system, as indicated by the correct answer. The urinary system includes the kidneys, ureters, bladder, and urethra, which are responsible for filtering blood and excreting waste in the form of urine.
Kidneys – Filter waste and excess fluids from the blood to form urine.
Ureters – Tubes that carry urine from the kidneys to the bladder.
Urinary Bladder – Stores urine before it is expelled from the body.
Urethra – A tube that allows urine to exit the body.
This system plays a crucial role in maintaining the body's fluid balance and removing waste products.
Pregunta 25 Informe
An air force jet flying with a speed of 335m/s went past an anti-aircraft gun. How far is the aircraft 5s later when the gun was fired?
Detalles de la respuesta
To solve this problem, we need to determine how far the aircraft travels in the 5 seconds after it passes the anti-aircraft gun. The problem gives us two key pieces of information:
To find the distance traveled, we use the formula for distance:
Distance = Speed × Time
Plugging in the given values:
Distance = 335 m/s × 5 s
Calculating this, we get:
Distance = 1675 meters
This means the aircraft is 1675 meters away from the point where it passed the anti-aircraft gun after 5 seconds.
Pregunta 26 Informe
Photometer is used to measure
Detalles de la respuesta
A photometer is an instrument designed to measure the intensity of light. It is used to determine how much light is received over a particular area. Photometers are vital in various fields such as photography, astronomy, and laboratory science for ensuring that light levels are appropriate for specific applications.
The device operates by assessing the brightness or illumination coming from a light source and comparing it with a standard light. The measurement can be displayed in different units such as lumens or lux, depending on the context of the measurement.
While photometers are focused on the intensity of light, they do not measure kinetic energy of liberated electrons, the frequency of light, or the wavelength of light. These quantities are measured using other specialized instruments, such as spectrometers or frequency analyzers.
Pregunta 27 Informe
In a solar panel, solar beam is concentrated by using
Detalles de la respuesta
In a solar panel system, the type of mirror used to concentrate solar beams is the Concave Mirror.
Explanation:
A concave mirror is a type of mirror that curves inward, like the inside of a bowl. This shape is very effective at focusing light. When sunlight hits a concave mirror, the mirror's shape causes the light beams to converge, or come together, at a single point known as the focus. This concentrated light can then be used to generate heat or electricity more efficiently.
Why not the others?
A convex mirror curves outward and disperses light beams rather than concentrating them.
A plane mirror has a flat surface and reflects light at the same angle it receives it, meaning it doesn't concentrate the beams.
A triangular mirror is not typically used in solar applications for concentrating light as its shape is not conducive to focusing beams effectively.
Therefore, a concave mirror is best suited for concentrating solar beams in solar panel systems.
Pregunta 28 Informe
The power of a convex lens of focal length 20cm is
Detalles de la respuesta
The power of a lens is a measure of its ability to converge or diverge light. It is defined as the reciprocal (or inverse) of the focal length of the lens. The formula for calculating the power (P) of a lens in diopters (D) is given by:
P = 1/f
where:
In this case, the focal length given is 20 cm. To apply the formula, we first need to convert this focal length into meters because the diopter is the reciprocal of the focal length in meters:
f = 20 cm = 0.20 m
Now, substitute the focal length in meters into the formula for power:
P = 1 / 0.20
P = 5.00 D
Thus, the power of the convex lens is 5.00 diopters. This indicates that the lens is capable of converging light at a distance of 5.00 meters.
Pregunta 29 Informe
A wheelbarrow inclined at 60º to the horizontal is pushed with a force of 150N. What is the horizontal component of the applied force
Detalles de la respuesta
When you push a wheelbarrow inclined at an angle to the horizontal, the applied force can be divided into two components: a **horizontal component** and a **vertical component**. To find the horizontal component of the force, you need to use the concept of resolving vectors.
The force of 150N is acting at an angle of 60º to the horizontal. The horizontal component of this force can be calculated using the cosine of the angle. The formula to determine the horizontal component \( F_{\text{horizontal}} \) is given by:
Fhorizontal = Fapplied \times \cos(\theta)
Where:
Substitute the values into the formula:
Fhorizontal = 150N \times \cos(60º)
We know that \(\cos(60º)\) equals 0.5.
Therefore:
Fhorizontal = 150N \times 0.5 = 75N
Thus, the **horizontal component** of the applied force is 75N.
Pregunta 30 Informe
The charge of magnitude 1.6 x 10 −19 C is placed in a uniform electric field of intensity 1200Vm−1 . Calculate its acceleration, if the mass of the charge is 9.1 x 10−31 kg
Detalles de la respuesta
To calculate the acceleration of a charge in an electric field, we start by determining the force acting on the charge. The force \( F \) experienced by a charge \( q \) in a uniform electric field \( E \) is given by the equation:
F = q * E
We are given:
Substituting these values into the equation for force:
F = 1.6 x 10-19 C * 1200 V/m
This results in:
F = 1.92 x 10-16 N
Next, we use Newton’s second law of motion to find the acceleration \( a \) of the charge. This law is given as:
F = m * a
Rearranging for \( a \), we have:
a = F / m
We know:
Substituting these values in the equation for acceleration:
a = \(\frac{1.92 x 10^{-16} N}{9.1 x 10^{-31} kg}\)
Calculating the above expression gives:
a ≈ 2.11 x 1014 ms-2
Therefore, the acceleration of the charge is approximately 2.11 x 1014 ms-2.
Pregunta 31 Informe
Bilateral symmetry,cylindrical bodies and double openings are characteristic features of
Detalles de la respuesta
Bilateral symmetry, cylindrical bodies, and double openings are characteristic features of nematodes. Nematodes, also known as roundworms, have a body structure that is symmetric along a single plane, which results in two mirror-image halves, thus exhibiting bilateral symmetry.
Furthermore, they usually have a cylindrical body shape, which means their bodies are long and narrow like a cylinder and taper at both ends. This shape helps them move through their environment easily. Additionally, nematodes have a complete digestive system with two openings: a mouth and an anus. This means that food enters through the mouth, gets digested, and waste exits through the anus.
In contrast, organisms like hydra, protozoa, and protists possess different anatomical features. Hydras, for example, typically show radial symmetry, and protozoa and protists generally do not have a well-defined body shape or bilateral symmetry as seen in nematodes. Therefore, the description fits nematodes best.
Pregunta 32 Informe
What is the colour of red rose under a blue light?
Detalles de la respuesta
To understand the color of a red rose under a blue light, we need to consider how we perceive color. Objects appear colored because they reflect certain wavelengths of light. A red rose appears red in white light because it reflects red wavelengths and absorbs others.
When you shine blue light on a red rose, the situation changes. A blue light primarily contains blue wavelengths. Since the red rose does not have red wavelengths to reflect anymore, and it cannot reflect blue light (as it absorbs it), the rose will appear to be the absence of any reflected wavelength visible to our eyes.
This means the rose will appear black under blue light, as black is perceived when no visible light is reflected into our eyes. Thus, the color of the red rose under a blue light is black.
Pregunta 33 Informe
If a body in linear motion changes from point P to Q, the motion is
Detalles de la respuesta
When a body moves in a straight line from one point, such as point P, to another point, such as point Q, the motion is called Translational Motion. This kind of motion refers to an object moving along a path in which every part of the object takes the same path as a reference point. This means that if you follow any point on the body, it covers the same amount of distance in the same time frame as any other point.
Let's break down the other options:
In conclusion, since the body is moving from point P to point Q along a straight line, it exhibits Translational Motion.
Pregunta 34 Informe
Two tuning forks of frequencies 6Hz and 4Hz respectively are sounded together. The beat frequency is
Detalles de la respuesta
When two sound waves of slightly different frequencies are sounded together, they interfere with each other in such a way that the intensity of the sound alternates between loud and soft. This phenomenon is known as "beats". The number of beats heard per second is called the "beat frequency".
The beat frequency can be calculated by subtracting the frequency of one wave from the frequency of the other. Mathematically, it is represented as:
Beat Frequency (fbeat) = | f1 - f2 |
Where:
In this case:
Using the formula:
fbeat = | 6Hz - 4Hz | = | 2Hz | = 2Hz
Therefore, the beat frequency is 2Hz. This means that you would hear 2 beats per second when the tuning forks of frequencies 6Hz and 4Hz are sounded together.
Pregunta 35 Informe
Calculate the upthrust on a spherical ball of volume 4.2 x 10−4 m3 when totally immersed in a liquid of density 1028kgm−3
Detalles de la respuesta
Upthrust(Force) = volume of object x density of liquid x g = V x ρ x g
U = 4.2 x 10−4 x 1028 x 10 ≊ 4.3N
Pregunta 36 Informe
An example of a non-rechargeable cell is
Detalles de la respuesta
A non-rechargeable cell, commonly known as a primary cell, is a type of chemical battery that is designed to be used once until the chemical reactions that produce electricity are exhausted. After this point, the cell cannot be reversed or recharged.
In the given examples, the dry leclanche cell is a well-known example of a non-rechargeable cell. It is commonly used in everyday devices like remote controls, wall clocks, and torches. This cell type utilizes zinc and manganese dioxide as electrodes and relies on a moist paste of ammonium chloride for the electrolyte.
The other examples, such as nickel iron, mercury cadmium, and lead-acid, involve rechargeable cells (secondary cells) that are specifically designed to endure multiple charges and discharges throughout their useful life. Thus, unlike the dry leclanche cell, these can be recharged after use.
Therefore, the dry leclanche cell is an ideal example of a non-rechargeable cell because it can only be used once. After depletion, it cannot be recharged or reused.
Pregunta 37 Informe
Which of the following measuring instruments operates based on the heating effect of electric current?
Detalles de la respuesta
Hot wire ammeters measure current by detecting the heat produced in a wire due to the electric current flowing through it.
Pregunta 38 Informe
The property by which a material returns to its original shape after the removal of force is called
Detalles de la respuesta
The property by which a material returns to its original shape after the removal of force is called Elasticity.
Let's break it down:
Elasticity: This is a property of a material that allows it to return to its original shape or size after the force that caused deformation is removed. Think of a rubber band—you can stretch it, but once you let it go, it snaps back to its initial shape.
Ductility: This property refers to a material's ability to be stretched into a wire. For example, materials like copper are ductile because they can be drawn into thin wires without breaking.
Malleability: This is a material's ability to withstand deformation under compressive stress. It is the property that allows metals to be hammered or rolled into thin sheets. Gold is a good example of a malleable metal.
Plasticity: This property describes the material's ability to undergo permanent deformation without breaking. When a plastic region is reached, the material will not return to its original shape after the removal of force.
Therefore, when we speak of a material returning to its original shape after the removal of force, we are specifically referring to Elasticity.
Pregunta 39 Informe
Infra-red thermometers work by detecting the
Detalles de la respuesta
Infra-red thermometers work by detecting the radiation from the body and converting it to temperature. These thermometers are designed to measure the infrared radiation, also known as heat radiation, emitted by objects. All objects with a temperature above absolute zero emit infrared radiation. The thermometer's sensor captures this radiation and converts it into an electrical signal that can be read as a temperature measurement. This method allows for quick, non-contact temperature readings, which is why infrared thermometers are often used in medical settings, industrial applications, and more.
Pregunta 40 Informe
The energy of light of frequency 2.0 x 1015 Hz is (h = 6.63 x 10−34 Js)
Detalles de la respuesta
To determine the energy of light given its frequency, we can utilize the formula:
E = h × f
Where:
E is the energy of the photon in joules (J)
h is Planck's constant, approximately 6.63 × 10-34 J·s
f is the frequency of light in hertz (Hz)
Given the frequency f = 2.0 × 1015 Hz, we can substitute the known values into our equation:
E = 6.63 × 10-34 J·s × 2.0 × 1015 Hz
To simplify the calculation, multiply the numerical parts and then add the indices of 10:
E = (6.63 × 2.0) × (10-34 × 1015)
E = 13.26 × 10-19 J
This can be approximated to 1.33 × 10-18 J. Thus, the energy of light with the given frequency is 1.33 × 10-18 J.
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