Electric Charges and Fields — Physics STD 12 Science — Question

When a plane mirror is rotated through an angle θ then the reflected ray turns through the angle 2θ then the size of the image

(a) Is doubled

(b) Is halved

(c) Remains the same

(d) Becomes infinite

Under what condition the force acting on the charge particle moving in the magnetic field maximum?

The X-ray beam coming from an X-ray tube will be

(a) Monochromatic

(b) Having all wavelengths smaller than a certain maximum wavelength

(c) Having all wavelengths larger than a certain minimum wavelength

(d) Having all wavelengths lying between a minimum and a maximum wavelength

An electric wire of length ‘I’ and area of cross-section a has a resistance R ohms. Another wire of the same material having same length and area of cross-section 4a has a resistance of

(a) 4R

(b) R/4

(c) R/16

(d) 16R

In the context of Doppler effect in light, the term ‘red shift’ signifies

(a) Decrease in frequency	(b) Increase in frequency
(c) Decrease in intensity	(d) Increase in intensity

Resistances of 6 ohm each are connected in the manner shown in adjoining figure. With the current 0.5 ampere as shown in figure, the potential difference  is

(a) 3.6 V

(b) 6.0 V

(c) 3.0 V

(d) 7.2 V

A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point Q lies to the west at the same distance the magnetic field at P is:

A curve between magnetic moment and temperature of magnet is

(a)

(b)

(c)

(d)

In a junction diode, the holes are due to

(a) Protons

(b) Neutrons

(c) Extra electrons

(d) Missing of electrons

Core of elctromagnets are made of ferromagnetic materials which have: