Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

In a series LCR circuit, the voltages across an inductor, a capacitor and a resistor are 30 V, 30 V and 60 V respectively. What is the phase difference between the applied voltage and the current in the circuit?

Can a hydrogen atom emit characteristic X-rays?

When a body is weighed on an ordinary balance we demand that the arm should be horizontal if the weights on the two pans are equal. Suppose equal weights are put on the two pans, the arm is kept at an angle with the horizontal and released. Is the torque of the two weights about the middle point (point of support) zero? Is the total torque zero? If so, why does the arm rotate and finally become horizontal?

A van of mass 1500kg travelling at a speed of 54kmh^-1 is stopped in 10s. Assuming that all the mechanical energy lost appears as thermal energy in the brake mechanism, find the average rate of production of thermal energy is cals^-1.

A particle executes simple harmonic motion. Let P be a point near the mean position and Q be a point near an extreme. The speed of the particle at P is larger than the speed at Q. Still the particle crosses P and Q equal number of times in a given time interval. Does it make you unhappy?

The speeds of red light and yellow light are exactly same:

1. In vacuum but not in air.
2. In air but not in vacuum.
3. In vacuum as well as in air.
4. Neither in vacuum nor in air.

A person is viewing an extended object. If a converging lens is placed in front of his eyes, will he feel that the size has increased?

Define the following :
Interference of light