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

The plate resistance of a triode is 2.5 × 10⁴ W and mutual conductance is 2 × 10^–3 mho. What will be the value of amplification factor

(a) 50

(b) 1.25 × 107

(c) 75

(d) 2.25 × 107

Mark the correct options:

1. If the incident rays are converging, we have a real object.
2. If the final rays are converging, we have a real image.
3. The image of a virtual object is called a virtual image.
4. If the image is virtual, the corresponding object is called a virtual object.

If the capacitors having capacitance C₁ and C₂ are connected in parallel then their effective capacitance is given by:

A current of 10 ampere is flowing in a wire of length 1.5 m. A force of 15 N acts on it when it is placed in a uniform magnetic field of 2 tesla. The angle between the magnetic field and the direction of the current is

(a) 30 °

(b) 45 °

(c) 60 °

(d) 90 °

The amount of substance liberated on electrodes during electrolysis when 1 coulomb of electricity is passed, is

(a) Chemical equivalent	(b) Electrochemical equivalent
(c) Equivalent weight	(d) One mol

Ultraviolet spectrum can be studied by using a:

Light of a particular frequency υ is incident on a metal surface. When the intensity of incident radiation is increased, the photoelectric current?

The bending of beam of light around corners of obstacles is called

(a) Reflection

(b) Diffraction

(c) Refraction

(d) Interference

Photons of energy 6 eV are incident on a metal surface whose work function is 4 eV. The minimum kinetic energy of the emitted photo-electrons will be

(a) 0 eV

(b) 1 eV

(c) 2 eV

(d) 10 eV

When a battery is connected across a series combination of self inductance L and resistance R, the variation in the current i with time t is best represented by

(a)

(b)

(c)

(d)