Alternating Current — Physics STD 12 Science — Question

The emf of a cell always greater than its terminal voltage. Why? Give reason.

Name the logic gate whose repetitive use can make digital circuits.

Two blocks of masses 10kg and 20kg moving at speeds of 10ms^-1 and 20ms^-1 respectively in opposite directions, approach each other and collide. If the collision is completely inelastic, find the thermal energy developed in the process.

How does the mobility of electrons in a conductor change, if the potential difference applied across the conductor is doubled, keeping the length and temperature of the conductor constant?

What does the graph look like between stopping potential and frequency of incident light?

For which colour the value of deviation angle is maximum and minimum?

The stopping potential in an experiment on photoelectric effect is 1.5 V. What is the maximum kinetic energy of the photoelectrons emitted?

The dielectric constant of the material kept between the plates of a capacitor is 5 and its capacitance is C. If it is replaced with a material having dielectric constant 20, then what will be the new capacitance of the capacitor?

An experimenter measures the length of a rod. In the cases listed, all motions are with respect to the lab and parallel to the length of the rod. In which of the cases the measured length will be minimum?

1. The rod and the experimenter move with the same speed v in the same direction.
2. The rod and the experimenter move with the same speed v in opposite directions.
3. The rod moves at speed v but the experimenter stays at rest.
4. The rod stays at rest but the experimenter moves with the speed v.

A charge 'q' is moved from a point A above a dipole of dipole moment 'p' to a point B below the dipole in equatorial plane without acceleration. Find the work done in the process.