Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

what is the potential difference between two points, if 2J of work must be done to move a 4 mC charge from one point to another is:

The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 mT. What will be its value at the centre of the loop

(a) 250 m T

(b) 150 m T

(c) 125 m T

(d) 75 m T

The current in a simple series circuit is 5.0 amp. When an additional resistance of 2.0 ohms is inserted, the current drops to 4.0 amp. The original resistance of the circuit in ohms was

(a) 1.25

(b) 8

(c) 10

(d) 20

Speed of electromagnetic waves is the same:

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

The photoelectric threshold wavelength for potassium (work function being 2eV ) is

(a) 310 nm

(b) 620 nm

(c) 1200 nm

(d) 2100 nm

Suppose the pressure at the surface of mercury in a barometer tube is P₁ and the pressure at the surface of mercury in the cup is P_2,

1. P₁ = 0, P₂ = atmospheric pressure.
2. P₁ = atmospheric pressure P₂ = 0
3. P₁ = P₂ = atmospheric pressure.
4. P₁ = P₂ = 0

In helium nucleus, there are

(a) 2 protons and 2 electrons	(b) 2 neutrons, 2 protons and 2 electrons
(c) 2 protons and 2 neutrons	(d) 2 positrons and 2 protons

LCD stands for:

For a thermocouple, the temperature of inversion is that temperature at which thermo e.m.f. is

(a) Zero

(b) Maximum

(c) Minimum

(d) None of the above