WAEC SSCE - Physics - 2021 (Objective)

A rotating disc contains a set of holes in a circle. An air jet is directed onto the holes and a note of frequency 480 Hz is produced. If the number of holes is 20, calculate the speed of rotation of the disc.     

A current of 2A passes through a wire of resistance 4Ω for 3 minutes. Calculate the energy lost.   

A student wishes to measure the potential difference across a resistor,R. She has a galvanometer,G and some connecting wires.

What else does she need?
 

Which of the following curved surfaces will produce a real image? I. Concave mirror II. Convex mirror III. Diverging lens IV. Converging lens    

The following statements about a loudspeaker are correct except?        

The inductive reactance in a circuit of frequency 100Hz is 1ohms. Calculate the inductance of the inductor[π = 3.14]

Which of the following set of quantities have members which are all vectors?

Which of the sketched graphs below illustrates the correct variation of the gravitational force, Fg between two objects and the distance, d, between the centres?

A heat sensitive resistor made of a semiconductor is called? 

The handle of a screw jack is 35 cm long and pitch of the screw is 0.5 cm. What force must be applied at the end of the handle to lift a load of 2000N, if the efficiency of the jack is 30% [π = 22/7]?   

Which of the following statements about the universal gravitational constant, G, is true?  

The electrons in a cathode-ray tube are produced by?          

A wire of cross-sectional area 2π *  10\(^-{8}\) m\(2\) and resistivity 1.1 x 10\(^-{8}\) Ω m, has a resistance of 21Ω.

Calculate the length of the wire. [π=22/7]     

A metallic sphere is heated from 27°C to 200°C Without change of state. Which of the following  changes would have resulted from the heating?

Formation of hydrogen bubbles at the copper plate of a primary cell is called?    

Electric motor primarily converts?    

Which of the following statements is an effect of compressing gas molecules at constant temperature?      

The sketched graph represents a progressive wave moving from the left to the right. The period the wave is 0.125s.

Determine the values of the amplitude and wavelength, respectively, of the wave.

Which of the following statements about the molecules of solids and liquids is correct? They both   

The diagram above is an illustration of an a.c. circuit.Calculate the reactance of the capacitor. 

Which of the following statements best describes the particles in a solid at room temperature? They are    

The diagram illustrates the velocity- time graph of a body. Calculate the distance covered by the body during the motion

Which of the following factors does not affect the rate of evaporation of a liquid? 

According to Pascal's principle, the pressure in a fluid is always?     

Which of the following scientist suggested that moving particles exhibit wave properties?

A man weighing 200 N runs up a staircase in 5s. If the height of the staircase is 9 m, calculate the power of the man.   

Which of the following factors is not among that determines the resistance of a wire?

Which of the arrangements of radiations below shows decreasing order of wavelengths?   

The reason for laminating the soft iron core of a  transformer is to?   

Which of the following actions will increase capacitance of a parallel plate capacitor?

I. Decreasing the distance between the plates

II. Increasing the distance between the plates.

III. Increasing the area of the plates overlap.

IV. Avoiding the use of dielectric between the plate

Which of the following statements is not a characteristic of a plane progressive wave?     

An ice cube has mass of 20 g at 5°C. Calculate the energy required to raise its temperature to 0°C. [Specific heat capacity of ice = 2.1 J/g°c]

The components of vectors Q and R are (-3.0, 5.5) and (9.2, 4.4) respectively. Determine the components of Q + R.     

An atom that emits an a-particle?

Which of the following units is equivalent to the unit of electric current?

An electric pressing iron is connected to the mains using an insulated wire. wire becomes very hot.

The heat generated in the wire can be minimized by replacing the wire with one of?

Which of the following statements about distance and displacement is not correct?     

Which of the following quantities is not an example of force? 

A radioactive material has a half-life of 1.0 hour If 200.0 g of it was present at 6 a.m. on a certain day, how many grams will have decayed by 9 a.m. on the same day?

A stone is thrown horizontally with initial velocity 15m/s from a tower 20 m high. How long does it take to reach the ground? [g= 10m/s\(^2\)

A force of 10 N, acting continuously, increases the kinetic energy of an object from 20.J to 60 J. Find the distance moved by the object.   

Determine the speed of the wave.   

The distance between a node and its adjacent antinode of a transverse wave is equal to?    

An electric circuit consists of a resistor. a battery and a key. If the voltage of the battery is increased, there Would be an increase in the?  

Opening in the eye through which light passes to the retina is called the?   

The acceleration of a moving object can be determined from the?  

If the relative humidity of the atmosphere increases, the rate of evaporation of sweat from the human body?

A note produced by an instrument is distinguished from a similar note produced by another instrument by the?     

In the diagram above, a bulb is lit by drawing 2.0A from 440V a.c. source. Calculate the cost of keeping the bulb on for two days at $0.40 per kilowatt-hour.

A ball is swung in a horizontal circle of centre O with a constant speed. acceleration?