Electromagnetic Induction — Physics STD 12 Science — Question

In a full wave rectifiers, input ac current has a frequency ‘n’. The output frequency of current is

(a) n/2

(b) n

(c) 2n

(d) None of these

The carrier frequency generated by a tank circuit containing 1 nF capacitor and 10 mH inductor is

(a) 1592 Hz

(b) 1592 MHz

(c) 1592 kHz

(d) 159.2 Hz

The net resistance of an ammeter should be small to ensure that:

Towards the centre of sun

(a) Density decreases	(b) Pressure decreases
(c) Temperature decreases	(d) Density and pressure increases

A capacitor with air as the dielectric is charged to a potential of  100 volts. If the space between the plates is now filled with a dielectric of dielectric constant 10, the potential difference between the plates will be

(a) 1000  volts

(b) 100 volts

(c) 10 volts

(d) Zero

 characteristic X-ray refers to the transition

(a) n = 2to n = 1

(b) n = 3 to n = 2

(c) n = 3  to n = 1

(d) n = 4 to n = 2

If the focal length of a double convex lens for red light is  its focal length for the violet light is

(a)

(b) Greater than

(c) Less than

(d)

The electronic transition from n = 2 to n = 1 will produce shortest wavelength in:

Two positive charges of 20 coulomb  and Q coulomb are situated at a distance of 60 cm. The neutral point between them is at a distance of 20 cm from the 20 coulomb charge. Charge Q is

(a) 30 C

(b) 40 C

(c) 60 C

(d) 80 C

In Young's double slit experiment, the distance between the slits is 1 mm and that between slit and screen is 1 meter and 10th fringe is 5 mm away from the central bright fringe, then wavelength of light used will be

(a) 5000 Å

(b) 6000 Å

(c) 7000 Å

(d) 8000 Å