Semiconductor Electronics: Materials, Devices and Simple Circuits — Physics STD 12 Science — Question

Fast neutrons can easily be slowed down by

(a) The use of lead shielding	(b) Passing them through water
(c) Elastic collisions with heavy nuclei	(d) Applying a strong electric field

Assertion :   Base in a transistor is made very thin as compared to collector and emitter regions.                

Reason     : Due to thin base power gain and voltage gain is obtained by a transistor.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

50 Ω and 100 Ω  resistors are connected in series. This connection is connected with a battery of 2.4 volts. When a voltmeter of 100 Ω  resistance is connected across 100 Ω  resistor, then the reading of the voltmeter will be

(a) 1.6 V

(b) 1.0 V

(c) 1.2 V

(d) 2.0 V

Which of the following statements is incorrect about hysteresis

(a) This effect is common to all ferromagnetic substances

(b) The hysteresis loop area is proportional to the thermal energy developed per unit volume of the material

(c) The hysteresis loop area is independent of the thermal energy developed per unit volume of the material

(d) The shape of the hysteresis loop is characteristic of the material

Faraday's laws are consequence of conservation of

(a) Energy	(b) Energy and magnetic field
(c) Charge	(d) Magnetic field

Which one of the following have minimum wavelength

(a) Ultraviolet rays

(b) Cosmic rays

(c) X-rays

(d) γ - rays

1000 small water drops each of radius r and charge q coalesce together to form one spherical drop. The potential of the big drop is larger than that of the smaller drop by a factor of

(a) 1000

(b) 100

(c) 10

(d) 1

Two particles A and B of masses   and  respectively and having the same charge are moving in a plane. A uniform magnetic field exists perpendicular to this plane. The speeds of the particles are   and   respectively, and the trajectories are as shown in the figure. Then

(a)	(b)
(c)  and	(d)  and

Figure represents a glass plate placed vertically on a horizontal table with a beam of unpolarised light falling on its surface at the polarising angle of 57^o with the normal. The electric vector in the reflected light on screen S will vibrate with respect to the plane of incidence in a

(a) Vertical plane

(b) Horizontal plane

(c) Plane making an angle of 45o with the vertical

(d) Plane making an angle of 57o with the horizontal

Which logic gate produces LOW output when any of the inputs is HIGH?