# Introduction

## Trending Questions

**Q.**

If a body gives out 109 electrons every second how much time is required to get total charge of 1 C

**Q.**The amount of solar energy received on the earth's surface per unit time is defined as solar constant. The dimension of solar constant is:

- ML2T−2
- ML0T−3
- M2L0T−1
- MLT−2

**Q.**

If energy (E), velocity (V) and time (T) are chosen as the fundamental quantities, thendimensional formula of surface tension will be :

[E

^{-2}V^{-1}T^{-3}][E V

^{-2}T^{-1}][EV

^{-1}T^{-2}][EV

^{-2}T^{-2}]

**Q.**

What is the definition of equilibrium

**Q.**A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (C = velocity of light)

- E/C
- 2E/C2
- 2E/C2
- 2E/C

**Q.**

Area is a vector quantity. How?

**Q.**

The magnitude of any physical quantity

- depends on the method of measurement.
- does not depends on the method of measurement.
- is more in SI system than in CGS system.
- directly proportional to the fundamental units of mass, length and time.

**Q.**In the quadratic equation, pqx2−(p2+q2)x+pq=0, then find values of x.

- p, q
- p2+q2, p2q2
- pq, qp
- pq, qp

**Q.**The speed of light in vaccum (c), depends on two fundamental constants, the permeability of free space (μ0) and permittivity of free space (ϵ0). The speed of light is given by c=1√μ0ϵ0. The units of ϵ0 are N−1C2m−2. The units for μ0 are

- kg−1m−1C2
- kg m C−2
- kg−1mC2
- kg−1s−1C2

**Q.**A vessel contains a mixture of one mole of oxygen and two moles of nitrogen at 300 K. The ratio of the average rotational kinetic energy of O2 molecules to that of N2 molecules per degree of freedom is

- 1:1
- 2:1
- Depends on moment of inertia.
- 1:2

**Q.**The density of a material in CGS system of units is 4 g/cm3. In a system of units in which unit of length is 10 cm and unit of mass is 100 g, the value of density of material will be

- 40 unit
- 4 unit
- 0.4 unit
- 0.04 unit

**Q.**

**Find the value of cos **${210}^{\circ}$

**Q.**The electric field part of an electromagnetic wave in a medium is represented by

Ex=0;Ey=2.5 NC−1cos[(2π×106 rad s−1)t−(π×10−2 rad m−1)x];Ez=0. Then, the waves is

- Moving along x−direction with frequency 106 Hz and wavelength 200 m

- Moving along y−direction with frequency 2π×106 Hz and wavelength 200 m

- Moving along negative x− direction with frequency 106 Hz and wavelength 200 m
- Moving along x−direction with frequency 106 Hz and wavelength 100 m

**Q.**

At constant volume gas thermometer shows pressure reading of 50 cm and 90 cm of mercury at 0∘C and 100∘C respectively. When the pressure reading is 60 cm of mercury, the temperature is

- 25°C
- 40°C
- 12°C
- 12.5°C

**Q.**

Two thin circular discs of mass m and 4m, having radii of a and 2a, respectively, are rigidly fixed by a massless, rigid rod of length l=√24a through their centres. This assembly is laid on a firm and flat surface, and set rolling without slipping on the surface so that the angular speed about the axis of the rod is ω. The angular momentum of the entire assembly about the point 'O' is →L (see the figure). Which of the following statement(s) is(are) true?

- The magnitude of the z-component of →L is 55ma2ω
- The magnitude of angular momentum of centre of mass of the assembly about the point O is 81ma2ω
- The centre of mass of the assembly rotates about the z-axis with an angular speed of ω/5
- The magnitude of angular momentum of the assembly about its centre of mass is 17ma2ω/2

**Q.**Electric field in a plane electromagnetic wave is given by

E=50sin(500x−10×1010t) V/m.

The velocity of electromagnetic wave in this medium is :

(Given c= speed of light in vacuum)

- c
- 23c
- 32c
- c2

**Q.**Four charges q, -2q, +2q, -q are placed respectively at the corners of a square of side a cm .what will be the magnitude of electroc field at the centre of square

**Q.**

The dimensions of 1/μ0ε0. where symbols have their usual meanings, are

[L−1T]

[L−2T2]

[L2T−2]

[LT−1]

**Q.**The vector sum of two forces P and Q is minimum when the angle between them is

- π3
- π2
- π
- π4

**Q.**

How is velocity used in everyday life with examples?

**Q.**Young's modulus of steel is 1.9×1011 N/m2. When expressed in CGS units of dyne/cm2, it will be equal to

- 1.9×1010
- 1.9×1011
- 1.9×1013
- 1.9×1012

**Q.**1.) In scattering experiment, find the distance of closest approach, if a 6 MeV o-particle is used(1) 3.210-16m(3) 4.6 x 10-15 m(2) 2 x 10-14 m(4) 3.210-15 m

**Q.**

A boy is sitting in a merry-go-round which is moving at a constant speed of * 10 m/s*. This means that the boy is

At rest

Moving with no acceleration

In accelerated motion

Moving with uniform velocity.

**Q.**The average kinetic energy of one mole of gas per degree of freedom (on the basis of theory of gases)

- 32RT
- 12RT
- 32kT
- 14kT

**Q.**Can a metal sphere of radius 1cm hold a charge of 1 coulomb

**Q.**A six-foot-tall person is 72 inches tall. How many centimeters tall is a six-foot person?

- 172.88 cm
- 182.88 cm
- 152.88 cm
- 282.88 cm

**Q.**A plane electromagnetic wave propagating in the x−direction in vacuum has wavelength of 6.0 mm. The electric field is in the y−direction and its maximum magnitude is 33 Vm−1.

(i) The equation for the electric field as a function of x(m) and t(s) is.

[1 Mark]

- 11 sin[π(t−xc)]
- 33 sin[π×1011(t−xc)]
- 33 sin[π(t−xc)]
- 11 sin[π×10−11(t−xc)]

**Q.**

A bird moves from point (1, -2) to (4, 2).If the speed of the bird is 10m/sec . then the velocity vector of bird is?

**Q.**A plane electromagnetic wave, has frequency of 2.0×1010 Hz and its energy density is 1.02×10–8 Jm−3 in vacuum.

The amplitude of the magnetic field of the wave is close to:

(14πε0=9×109 Nm2C2)and speed of light c=3×108 ms−1

- 150 nT
- 160 nT
- 180 nT
- 190 nT

**Q.**

The de Broglie wavelength of 10 KeV electron is