Lenz’s law of electromagnet states that
- A. the induced charge is constant for a fixed change of force
- B. a force is exerted on a current-carrying conductor in a magnetic field
- C. the magnitude of the induced e.m.f in a circuit is proportional to the rate of change of the number of lines of force linking the circuit
- D. the induced current in a conductor is in such a direction as to oppose the change producing it
- E. e.m.f. is induced in a circuit whenever there is a change in the magnetic flux linked with the circuit
The diagram above illustrates a freely suspended bar magnet NS hanging from a point in a horizontal ceiling. The thread used for suspending the magnet and the axis of the magnet are as indicated on the diagram. The angle marked \(\theta\) is called the angle os
- A. depression
- B. declination
- C. variation
- D. elevation
- E. dip
Calculate the resistance of the filament of lamp rated at 240V 60W
- A. 240\(\Omega\)
- B. 360\(\Omega\)
- C. 960\(\Omega\)
- D. 144\(\Omega\)
- E. 2880\(\Omega\)
A cell of e.m.f. 1.5v is connected in series with a resistor of 3\(\Omega\). A high resistance voltmeter connected across the cell registers only 0.9v. Calculate the internal resistance of the cell
- A. 5.0\(\Omega\)
- B. 4.5\(\Omega\)
- C. 2.4\(\Omega\)
- D. 2.0\(\Omega\)
- E. 1.8\(\Omega\)
In the electrical method of magnetisation, the polarity of the magnet depends on the
- A. amount of current passed
- B. direction of current
- C. magnetic material used
- D. size of the magnetic material
- E. orientation of the magnetic material in space
The gravitational force of the moon is one-sixth that of the earth. If a body weighs 6.0N on the moon. Calculate its weight on the earth
- A. 36.0N
- B. 12.0N
- C. 6.0N
- D. 2.0N
- E. 1.0N
An electromagnetic wave of frequency 5.0 x 1014Hz, is incident on the surface of water of refractive index \(\frac{4}{3}\). Taking the speed of the wave in air as 3.0 x 108ms-1, calculate the wavelength of the wave in water.
- A. 2.2 x 10-6m
- B. 1.7 x 10-7m
- C. 8.0 x 10-7m
- D. 6.0 x 10-7m
- E. 4.5 x 10-7m
Which of the following are both mechanical and transverse?
- A. infra-red rays
- B. gamma rays
- C. sound waves
- D. water waves
- E. micro waves
Calculate he wavelength of a note which is one octave lower than a note of 256Hz in a medium in which the speed of sound is 352ms-1
- A. 0.69m
- B. 1.38m
- C. 2.75m
- D. 5.50m
- E. 9.30m
A sonometer wire under a tension of N10N, produces a frequency of 250Hz when plucked. Keeping the length of the wire constant, the tension is adjusted to produce a new frequency of 350Hz. Calculate the new tension
- A. 39.2N
- B. 19.6N
- C. 14.2N
- D. 7.4N
- E. 5.1N
the shortest length of the air column in a resonance tube at resonance is 0.12m and the next resonance length is 0.37m. calculate the frequency of vibration given that the speed of sound in air is 340m-1
- A. 1360Hz
- B. 694Hz
- C. 680Hz
- D. 34Hz
- E. 340Hz
The intensity of light falling on the film in a camera depend on the i. brightness of the object. ii. diameter of the aperture stop. iii. speed of the shutter. Which of the statements is/are correct/
- A. i, ii and iii
- B. i and ii only
- C. i and ii only
- D. ii and iii only
- E. iii only
A lantern gives an image of 3m square of a slide 7.62cm square on a screen. If the screen is 10m from the projection lens of the lantern, calculate the focal length of the lens
- A. 40.3cm
- B. 26.1cm
- C. 24.8cm
- D. 0.7cm
- E. 0.3cm
An astronomical telescope having an objective of focal length 100cm and an eyepiece of focal length 10cm is used in normal adjustment, calculate the separation of the lenses
- A. 0.10m
- B. 0.90cm
- C. 1.10m
- D. 1.80m
- E. 2.20m
A converging lens of focal length 5cm is used as a magnifying glass by a man whose nearpoint is 35cm. Calculate the magnification given by the lens
- A. 8
- B. 7
- C. 6
- D. 5
- E. 4
The images formed by diverging lenses are always
- A. diminished, virtual and inverted
- B. diminished, virtual and errect
- C. diminished inverted and real
- D. magnidied, virtual and errect
- E. magnified, real and inverted
What is the image distance of an object placed at a distance of 2f from a converging lens of focal length f?
- A. f/4
- B. f/2
- C. f
- D. 2f
- E. 4f
The phenomenon which occurs when light changes direction as it passes from one medium to another is called
- A. reflection
- B. polarisation
- C. interference
- D. diffraction
- E. refraction
An eclipse of the sun by the moon occurs when the sun, the moon and the earth are in a straight line and the
- A. earth casts a shadow on the moon
- B. moon casts a shadow on the sun
- C. moon is between the sun and the earth
- D. earth is between the sun and the moon
- E. sun is between the moon and the earth
If an ebonite rod is rubbed with fur
- A. both the ebonite rod and the fur will be negatively charged
- B. the ebonite rod will be positively charged while the fur will have no charge
- C. there will be electron transfer only if the ebonite rod is earthed
- D. the ebonite rod will be negatively charged while the fur will be positively charged
- E. the ebonite rod will be positively charged while the fur will be negatively charged
A 90-W immersion heater is used to supply energy for five minutes. The energy supplied is used to completely melt 180g of a solid at is melting point. Neglecting energy losses to the surroundings, calculate the specific latent heat of fusion of the solid
- A. 0.5Jg-1
- B. 2.5Jg-1
- C. 15.0Jg-1
- D. 450.0Jg-1
- E. 150Jg-1