Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Assertion :  A transistor is a voltage-operating device.

Reason     : Base current is greater than the collector current.

(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.

Three capacitances of capacity 10 μF, 5 μF  and 5 μF  are connected in parallel. The total capacity will be

(a) 10 μF

(b) 5 μF

(c) 20 μF

(d) None of the above

Dielectric constant of pure water is 81. Its permittivity will be

(a)   units	(b) 8.86  units
(c) 1.02  units	(d) Cannot be calculated

The age of universe is believed to be

(a) 1 billion years

(b) 10 billion years

(c) 10-20 billion years

(d) 1000 billion years

The majority charge carriers in P-type semiconductor are

(a) Electrons

(b) Protons

(c) Holes

(d)  Neutrons

White light is passed through a prism whose angle is 5°. If the refractive indices for rays of red and blue colour are respectively 1.64 and 1.66, the angle of deviation between the two colours will be

(a) 0.1 degree

(b) 0.2 degree

(c) 0.3 degree

(d) 0.4 degree

Speed of electromagnetic waves is the same:

1. For all wavelengths.
2. In all media.
3. For all intensities.
4. For all frequencies.

A beam consisting of protons and electrons moving at the same speed goes through a thin region in which there is a magnetic field perpendicular to the beam. The protons and the electrons:

If the forward voltage in a semiconductor diode is doubled, the width of the depletion layer will

(a) Become half

(b) Become one-fourth

(c) Remain unchanged

(d) Become double