Physics Past Questions and Answers

A transformer has 300 turns of wire in the primary coil and 30 turns in the secondary coil.If the input voltage is 100 volts, the output voltage is

A 5 volts
B 10 volts
C 15 volts
D 20 volts
E 25 volts

Question 42:

A closed coil of wire is placed near a magnet. The magnet lies along the axis of the coil. Under which of the following conditions would there be no current in the coil?

A When the coil is moved toward the stationary magnet
B When the coil is moved away from the stationary magnet
C When the coil is held stationary but the magnet is moved towards the coil
D When both the coil and the magnet are held stationary
E When the coil is held stationary but the magnet is moved away from the cell

Question 43:

If I is the current passing through a metallic resistor and H is the rate of Heat generated in the resistor at a constant temperature, then

A H \(\alpha\) \(\frac{1}{I}\)
B H \(\alpha\) \(\frac{1}{I^2}\)
C H \(\alpha\) \(\sqrt1\)
D H \(\alpha\) I²
E None of the above

Question 44:

A solid weighs 4.8g in air, 2.8g in water and 3.2g in kerosine. The ratio of density of the solid to that of the kerosine is

A 12
B 3
C 2
D \(\frac{3}{2}\)
E \(\frac{5}{4}\)

Question 45:

A body of mass 6kg rests on an inclined plane. The normal reaction is R and the limiting frictional force is F as shown in the image above. if F = 30N, and g = 10ms² then the angle of inclination \( \theta \) is

A \( 15^{\circ} \)
B \( 30^{\circ} \)
C \( 45^{\circ} \)
D \( 60^{\circ} \)
E \( 75^{\circ} \)