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

An NPN-transistor circuit is arranged as shown in figure. It is

(a) A common base amplifier circuit	(b) A common emitter amplifier circuit
(c) A common collector amplifier circuit	(d) Neither of the above

According to Maxwell's hypothesis, changing of electric filed give rise to.

According to modern astronomers into how many constellations, the whole sky is divided

(a) 1011

(b) 88

(c) 880

(d) 5000

Which of the following are best suited to make the core of a transformer?

A square conducting loop of side L and resistance R is moving in its plane with a uniform velocity v perpendicular to its one side, where magnetic induction is B which is constant in space and time and is normal to the inwards of the plane. Induced current in the coil is:

The speed of an electron having a wavelength of   is

(a) 7.25 ×

(b) 6.26 ×

(c) 5.25 ×

(d) 4.24 ×

Infrared radiation was discovered in 1800 by

(a) William Wollaston

(b) William Herschel

(c) Wilhelm Roentgen

(d) Thomas Young

and   ions having same kinetic energy pass through a region of space filled with uniform magnetic field B directed perpendicular to the velocity of ions. The masses of the ions  and  are respectively in the ratio 1 : 4 : 16. As a result

(a)  ions will be deflected most

(b)  and   ions will suffer same deflection

(c) All ions will suffer the same deflection

(d) a, b

The momentum of photon is :

Three charges Q(+q)  and (+q)  are placed at the vertices of an equilateral triangle of side l as shown in the figure. If the net electrostatic energy of the system is zero, then Q is equal to

(a)

(b) (-q)

(c) (+q)

(d) Zero