MHT - CET MCQ

In a transistor, the thickness of the base region ____________.

The activity of a radioactive sample ____________.

The electron of mass 'm' is rotating in first Bohr orbit of radius 'r' in hydrogen atom. The orbital acceleration of the electron in first orbit is ______.

(b =Planck's constant)

For a certain atom when the system moves from 2E level to E, a photon of wavelength `lambda` is emitted. The wavelength of photon produced during its transition from `(4"E")/3` level to E is ____________.

A particle of charge q, mass m and energy E has de-Broglie wavelength `lambda.` For a particle of charge 2q, mass 2m and energy 2E, the de-Broglie wavelength is ____________.

Which one of the following is TRUE in photoelectric emission?

In rejector circuit, above resonant frequency the circuit is ____________.

The voltage gain of a CE amplifier is 50. A sinusoidal ac of amplitude 10 mV is applied as a signal. The output of the amplifier will be ______.

The reactance of a capacitor in an A.C. circuit is 20 Ω. If the frequency of A.C. is doubled, its reactance will become ______.

The magnetic potential energy stored in a certain inductor is 15 mJ, when the current in the inductor is 40 mA. This inductor is of inductance ____________.

An electron moves on a straight line path XY as shown. The abed is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil? 

A small quantity of paramagnetic liquid is taken in a watch - glass and kept on two dissimilar magnetic poles. The liquid ____________.

A circular arc of radius 'r' carrying current 'I' subtends on angle `pi/16` at its centre. The radius of a metal wire is uniform. The magnetic induction at the centre of circular arc is ____________.

The magnetic field at the centre of coil of n turns, bent in the form of a square of side `2l`, carrying current i, is ____________.

In an ammeter 0.2 % of main current passes through the galvanometer. If resistance of galvanometer is G, the resistance of ammeter will be ____________.

If the length of potentiometer wire is increased, then the length of the previously obtained balance point will ______.

In the given figure, battery E is balanced on 55 cm length of potentiometer wire but when a resistance of 10 `Omega` is connected in parallel with the battery, then it balances on 50 cm length of the potentiometer wire. The internal resistance r of the battery is ____________. 

Two cells when connected in series are balanced on 8 m on a potentiometer. If the cells are connected with polarities of one of the cell reversed, they balance on 2 m. The ratio of e.m.f's of the two cells is ____________.

The resistance of the potentiometer wire should ideally be ____________.

The figure shows a network of currents. The magnitude of currents is shown here. The current I will be ______ 

When wavelength of light used in optical instruments A and B are 4500 Å and 6000 Å respectively, the ratio of resolving power of A to B will be ______.

For Fraunhofer diffraction to occur ____________.

When unpolarised light is passed through crossed polaroids, then light passing through the first polaroid ______

A pipe closed at one end produces a fundamental note of frequency 'v'. It is cut into two pipes of equal length. The fundamental frequencies produced in the two pipes are ______.

Two waves represented by the following equations are travelling in the same medium

`y_1 = 5 sin 2pi(75t - 0.25 x)`

`y_2 = 10 sin 2pi(150t - 0.50 x)`

The intensity ratio `"I"_1/"I"_2` of the two waves is ______

Two simple pendulums A and B are made to oscillate simultaneously and it is found that A completes 10 oscillations in 20 sec and B completes 8 oscillations in 10 sec. The ratio of the lengths of A and B is ____________.

Kirchhoff's law of radiation proves that a good emitter is a ______.

If a capillary tube is dipped in water in a state of weightlessness, then water will ______.

Three charges +Q, q, +Q are placed respectively, at distance, 0, d/2 and d from the origin, on the X-axis. If the net force experienced by +Q, placed at x = 0, is zero then value of q is ____________.

A 4.5 cm long needle is placed 10 cm away from a convex mirror of focal length 16 cm. Locate the image of the needle from the mirror.

A metal sphere cools from 66° C to 57° C in 10 minutes and to 44° C in the next 10 minutes. The ratio of fall of temperature of first 10 minutes to next ten minutes is ____________.

Two satellites of a planet have periods of 32 days and 256 days. If the radius of the orbit of the former is R, the orbital radius of the Latter is ______

If two balls each of mass 60 g moving in opposite directions with speed 3.5 m/s collide and rebound with the same speed, then the impulse imparted to each ball due to other is ____________.

Certain neutron stars are believed to be rotating at about 1 rev/s. If such a star has a radius of 1.6 km, the acceleration of an object on the equator of the star will be nearly ____________.

A particle goes round a circular path with uniform speed v. After describing half the circle, what is the change in its centripetal acceleration?