Magnetism And Matter — Physics STD 12 Science — Question

Two identical coaxial circular loops carry current i each circulating in the clockwise direction. If the loops are approaching each other, then              (a) Current in each loop increases(b) Current in each loop remains the same(c) Current in each loop decreases(d) Current in one-loop increases and in the other it decreases

In a movie hall, the distance between the projector and the screen is increased by 1% illumination on the screen is(a) Increased by 1%(b) Decreased by 1%(c) Increased by 2%(d) Decreased by 2%

A long, hollow conducting cylinder is kept coaxially inside another long, hollow conducting cylinder of larger radius. Both the cylinders are initially electrically Neutral.

Assertion   :   Electric appliances with metallic body; e.g. heaters, presses etc, have three pin connections, whereas an electric bulb has a two pin connection.
Reason    : Three pin connections reduce heating of connecting cables.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

A solid floats in a liquid in a partially dipped position.

1. The solid exerts a force equal to its weight on the liquid.
2. The liquid exerts a force of buoyancy on the solid which is equal to the weight of the solid.
3. The weight of the displaced liquid equals the weight of the solid.
4. The weight of the dipped part of the solid is equal to the weight of the displaced liquid.

Hydrogen bomb is based on:

The electromagnetic waves travel with a velocity(a) Equal to velocity of sound(b) Equal to velocity of light(c) Less than velocity of light(d) None of these

In a laboratory experiment on emission from atomic hydrogen in a discharge tube, only a small number of lines are observed whereas a large number of lines are present in the hydrogen spectrum of a star. This is because in a laboratory:

1. The amount of hydrogen taken is much smaller than that present in the star.
2. The temperature of hydrogen is much smaller than that of the star.
3. The pressure of hydrogen is much smaller than that of the star.
4. The gravitational pull is much smaller than that in the star.