NECO SSCE - Physics - 2001

The main function of the commutator in a simple d.c. motor is to

A metal has a work function of 3.0 eV. What is the threshold frequency of the metal when electrons are just liberated from the metal.(1 eV = 1.6 × 10-19J; h = 6.6 × 10-34Js)

What is X in the equation given below? 42He + 94Be → 126C + X

A 220 V, 60 Hz alternating current supply is connected to an inductor of 3.5H. What is the current passing through the inductor?

In 24 days a radioactive isotope decreases in mass from 128g to 2g. What is the half-life of the radioactive material?

Which scientist discovered natural radioactivity?

The inside of a vacuum flask is usually coated with silver to reduce heat loss by

Which statement is TRUE of a block of stone of mass m, with zero momentum?

A wave is represented by the equation y = 0.5 sin 0.4 Ω(X - 60t), where the distance (X) is measured in centimetres and time (t) in seconds. What is the wave length of the wave?

N.N.P.C. gas cylinder containing 15kg of cooking gas was left open, and the gas emptied in 3.8 minutes, at an average speed of 20 ms^-1. What force was exerted on the gas in the cylinder?

Which statement about the concept of temperature is NOT true?

When water is heated between 0°C and 4°C, it's density

Which is NOT one of the laws of solid friction?

Which is a stringed Instrument?

A body whose initial velocity is u is uniformly accelerated to a final velocity v in t seconds. If the distance travelled is s, and the acceleration is a, which equation is INCORRECT for the motion of the body?

The speed of sound travelling in various media increases in the order:

What is the angular velocity of an object in a horizontal circular path of radius 1.5m with a constant speed of 12ms^-1?

Notes of the same frequency sounded on a piano and on a flute may differ in

I. pitch
II. quality
III. Loudness

Which statement is NOT correct about molecules?

A cell can supply currents of 0.60 A and 0.30 A through a 2.0 ω and a 5.0 ω resistor respectively. What is the internal resistance of the cell?

If N.E.P.A. charges 65 kobo per kilowatt-hour for electricity supplied to consumers, what bill would an electric iron rated at 750 watts attract when used for 24 hours?

An object placed 15cm from a converging lens forms a real image whose magnification is 2.0. What is the focal length of the lens?

An object 3.00m high is placed at a distance of 7.50m from a pin-hole camera. If the image height is 6.00 cm, what is the distance of the film from the pin-hole?

What is the energy stored in a 10μ F capacitor if the potential difference between the plates is 40 V?

When an astronomical telescope is in normal adjustment, the focal length of the objective lens is 50cm and that of the eye piece is 5.0cm. What is the distance between the lenses?

The statement that the mechanical advantage of a machine is 3 means that the

The falling of light energy on a metal such that electrons are liberated from the metal is called

How much heat is required to convert 5.0g of ice at 0 ° C to water at the boiling point? (Specific latent heat of ice = 336Jg^-1 specific heat capacity of water = 4.2Jg^-1K^-1)

Which material is best for making a permanent magnet?

What part of a camera functions in a similar way to the retina of the eye?

The lower and upper fixed points of a mercury-in-glass thermometer are marked X and 180 mm respectively. On a particular day the mercury meniscus in the thermometer rises to 60mm. If the corresponding reading on a Celsius scale is 20 ° C, what is the value X?

A transformer is connected to a 250 V a.c. supply. The primary coil has 5000 turns and the secondary voltage is found to be 10 V. What is the number of turns in the secondary coil?

The invisible part of the spectrum of white light consists of

The magnetic effect of a current-carrying coil is NOT utilized in the making of a/an

What gives rise to the line spectra observed in atoms?

The wavelength of a stationary wave is 24.0cm. What is the distance between a node and the next antinodes?

A lead-acid accumulator is used in preference to a dry battery in a car because

Given the same amount of beat, a quantity of water will reach a higher temperature in a brass pot than in a clay pot of the same mass because

An electron of charge a = 1.6 × 10^-19C is situated in a uniform electric field of intensity 2.4 × 105 V m^-1. What is the force on the electron?

Which statements(s) is/are NOT true?

I. A saturated vapour is one that is in equilibrium with its liquid in a closed space. II. A vapour contains molecules with varying kinetic energy and their distances apart are smaller than those of the molecules of a liquid
III. Relative Humidity = \(\frac{\text{Saturated vapour pressure at dew point}} {\text{Saturated vapour pressure at air temperature}}\) x 100%

IV. The saturated vapour pressure of water increases with temperature

50cm³ of air at a pressure of 5Nm^-2 is enclosed in a metal tube by a piston. If the piston is pushed in a distance of 10cm, what will the pressure of the air become, if the cross-sectional area of the tube is 2cm^-2? (Assume that the temperature remains constant throughout)

An object is placed 15cm in front of a concave mirror of focal length 20cm. The image formed is

Totally reflecting prisms are preferred to mirrors in periscopes because

I. mirror givegive multiple images
II. silvering on mirrors is easy damaged
III. mirrors reflect less light than totally reflecting prisms

An astronaut is walking on the moon where the magnitude of the acceleration due to gravity "g’ is one-sixth that on earth. Compared with their magnitudes on the earth, his mass and weight on the moon are

A waterfall is 630m high. What is the change in temperature of a quantity of water that falls from the top to the bottom of the waterfall? (Neglect heat losses to the surroundings, take g as 10 ms-2 and specific heat capacity of weather as 4200,J kg-1K-1

Which statement is a correct consequence of the uncertainly principle?