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

Optical fibre communication is based on which of the following phenomena :

 Identify the electromagnetic wave which is also known as heatwaves.

10 wires (same length, same area, same material) are connected in parallel and each has 1 Ω resistance, then the equivalent resistance will be

(a) 10 Ω

(b) 1 W

(c) 0.1 W

(d) 0.001 W

If the luminous intensity of a 100 W unidirectional bulb is 100 candela, then total luminous flux emitted from the bulb is

(a) 861 lumen

(b) 986 lumen

(c) 1256 lumen

(d) 1561 lumen

The output in the circuit of figure is taken across a capacitor. It is as shown in figure

(a)

(b)

(c)

(d)

A capacitor is charged by using a battery which is then disconnected. A dielectric slab is then slipped between the plates, which results in

(a) Reduction of charge on the plates and increase of potential difference across the plates

(b) Increase in the potential difference across the plate, reduction in stored energy, but no change in the charge on the plates

(c) Decrease in the potential difference across the plates, reduction in the stored energy, but no change in the charge on the plates

(d) None of the above

The magnitude of electric field intensity E is such that, an electron placed in it would experience an electrical force equal to its weight is given by

(a) mge

(b)

(c)

(d)

The pressure of a gas kept in an isothermal container is 200kPa. If half the gas is removed from it, the pressure will be:

1. 100kPa.
2. 200kPa.
3. 400kPa.
4. 800kPa.

Image of any object formed at the retina of human eye is :