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

A far sighted man who has lost his spectacles, reads a book by looking through a small hole (3-4 mm) in a sheet of paper. The reason will be

(a) Because the hole produces an image of the letters at a longer distance

(b) Because in doing so, the focal length of the eye lens is effectively increased

(c)  Because in doing so, the focal length of the eye lens is effectively decreased

(d) None of these

Consider the motion of the tip of the minute hand of a clock. In one hour:

1. The displacement is zero.
2. The distance covered is zero.
3. The average speed is zero.
4. The average velocity is zero.

For a thermocouple the neutral temperature is 270℃  when its cold junction is at 20℃. What will be the neutral temperature and the temperature of inversion when the temperature of cold junction is increased to 40 ℃

(a) 290℃, 580℃

(b) 270℃, 580℃

(c) 270℃, 500 ℃

(d) 290 ℃, 540 ℃

A flake of glass (refractive index 1.5) is placed over one of the openings of a double slit apparatus. The interference pattern displaces itself through seven successive maxima towards the side where the flake is placed. if wavelength of the diffracted light is λ = 600nm, then the thickness of the flake is

(a) 2100 nm

(b) 4200 nm

(c) 8400 nm

(d) None of these

A direct current of 4 A is flowing through any circuit. Root mean square value of the current is:

In a single slit diffraction experiment first minimum for red light (660 nm) coincides with first maximum of some other wavelength l'. The value of l' is

(a) 4400 Å

(b) 6600 Å

(c) 2000 Å

(d) 3500 Å

The velocity of light emitted by a source S observed by an observer O, who is at rest with respect to S is c. If the observer moves towards S with velocity v, the velocity of light as observed will be

(a) c + v

(b) c - v

(c) c

(d)

Two uncharged bodies on rubbing, get charged due to:

The magnetic flux linked with coil, in weber is given by the equation,  The induced emf in the coil in the fourth second is

(a) 10 V

(b) 30 V

(c)  45 V

(d) 90 V

Which of the following plots may represent the reactance of a series LC combination?