Electric Charges and Fields — Physics STD 12 Science — Question

Figure shows a smooth inclined plane fixed in a car accelerating on a horizontal road. The angle of incline 0 is related to the acceleration a of the car as a = g tan°. If the sphere is set in pure rolling on the incline:

1. It will continue pure rolling.
2. It will slip down the plane.
3. Its linear velocity will increase.
4. Its linear velocity will slowly decrease.

Three photons coming from excited atomic-hydrogen sample are picked up. Their energies are 12.1eV, 10.2 eV and 1.9eV. These photons must come from:

1. A single atom.
2. Two atoms.
3. Three atoms.
4. Either two atoms or three atoms.

Light from sodium lamp is passed through cold sodium vapours, the spectrum of transmitted light consists of(a) A line at 5890 Å (b) A line at 5896 Å(c) Sodium doublet lines(d) No spectral features

Alternating current cannot be measured by de ammeter because:

Half life of a radio-active substance is 20 minutes. The time between 20% and 80% decay will be(a) 20 minutes(b) 40 minutes(c) 30 minutes(d) 25 minutes

Which of the following pairs of physical quantities may be represented in the same unit?

1. Heat and temperature.
2. Temperature and mole.
3. Heat and work.
4. Specific heat and heat.

Which of the following is used as a moderator in nuclear reactors(a) Uranium(b) Heavy water(c) Cadmium(d) Plutonium

The angular velocity of the engine (and hence of the wheel) of a scooter is proportional to the petrol input per second. The scooter is moving on a frictionless road with uniform velocity. If the petrol input is increased by 10%, the linear velocity of the scooter is increased by:

1. 50%
2. 10%
3. 20%
4. 0%