Ray Optics and Optical Instruments — Physics STD 12 Science — Question

As the temperature of a metallic resistor is increased, the product of its resistivity and conductivity:

1. Increases.
2. Decreases.
3. Remains constant.
4. May increase or decrease.

Compton effect is associated with

(a) α -  rays

(b) β -  rays

(c) X-rays

(d) Positive rays

In a PNP transistor the base is the N-region. Its width relative to the P-region is

(a) Smaller

(b) Larger

(c) Same

(d) Not related

The rest mass of an electron as well as that of positron is 0.51 MeV. When an electron and positron are annihilate, they produce gamma-rays of wavelength(s)

(a) 0.012 Å

(b) 0.024 Å

(c) 0.012 Å to ¥

(d) 0.024 Å to ¥

A metallic particle having no net charge is placed near a finite metal plate carrying a positive charge. The electric force on the particle will be:

1. Towards the plate.
2. Away from the plate.
3. Parallel to the plate.
4. Zero.

When light falls on a metal surface, the maximum kinetic energy of the emitted photo-electrons depends upon

(a) The time for which light falls on the metal

(b) Frequency of the incident light

(c) Intensity of the incident light

(d) Velocity of the incident light

In the connections shown in the adjoining figure, the equivalent capacity between A  and  B will be

(a) 10.8 μF

(b) 69 μF

(c) 15 μF

(d) 10 μF

The graph that correctly represents the relation of frequency n of a particular characteristic X-ray with the atomic number Z of the material is

(a)

(b)

(c)

(d)

The minimum wavelength of X-ray emitted by X-rays tube is 0.4125 Å. The accelerating voltage is

(a) 30 kV

(b) 50 kV

(c) 80 kV

(d) 60 kV

For a series LCR circuit the power loss at resonance is : -