Physics 2022 Question Paper Online Test (12th Standard)

Q1

Which one of the following is the natural nanomaterial ?

A.Grain of sand B.Peacock feather C.Skin of the whale D.Peacock beak

Q2

In an electron microscope, the electrons are accelerated by a voltage of 14 kV. If the voltage is changed to 224 kV, then the de-Broglie wavelength associated with the electrons would :

A.decrease by 4 times B.increase by 2 times C.increase by 4 times D.decrease by 2 times

Q3

The variation of frequency of carrier wave with respect to the instantaneous amplitude of the modulating signal is called :

A.Phase modulation B.Amplitude modulation C.Pulse width modulation D.Frequency modulation

Q4

Q factor is equal to ________.

A.\(\frac{\omega_r L}{R}\) B.\(\frac{1}{R}\sqrt{\frac{L}{C}}\) C.\(\frac{X_L}{R}\) D.All the above

Q5

Two metallic spheres of radii 1 cm and 3 cm are given charges of \(-1 \times 10^{-2}\) C and \(5 \times 10^{-2}\) C respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is :

A.\(1 \times 10^{-2}\) C B.\(3 \times 10^{-2}\) C C.\(2 \times 10^{-2}\) C D.\(4 \times 10^{-2}\) C

Q6

Which of the following is an electromagnetic wave ?

A.β-rays B.γ-rays C.α-rays D.All of the above

Q7

An air bubble in glass slab of refractive index 1.5 (near normal incidence) is 5 cm deep when viewed from one surface and 3 cm deep when viewed from the opposite face. The thickness of the slab is :

A.12 cm B.8 cm C.16 cm D.10 cm

Q8

In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in USA will be :

A.R/4 B.R C.R/2 D.2R

Q9

A wire of length \(l\) carrying a current I along the Y direction is kept in a magnetic field given by \(\vec{B} = \frac{\beta}{\sqrt{3}}(\hat{i} + \hat{j} + \hat{k})\) T. The magnitude of Lorentz force acting on the wire is :

A.\(\sqrt{2}\,\beta I l\) B.\(\sqrt{\frac{2}{3}}\,\beta I l\) C.\(\sqrt{\frac{1}{2}}\,\beta I l\) D.\(\sqrt{\frac{1}{3}}\,\beta I l\)

Q10

Emission of electrons by the absorption of heat energy is called ________ emission.

A.Thermionic B.Photo electric C.Secondary D.Field

Q11

If a current of 7.5 A is maintained in a wire for 45 seconds then the charge flowing through the wire is :

A.6 C B.365.5 C C.3 C D.337.5 C

Q12

The charge of cathode ray is :

A.neutral B.positive C.not defined D.negative

Q13

A step-down transformer reduces the supply voltage from 220 V to 11 V and increases the current from 6 A to 100 A. Then its efficiency is :

A.0.12 B.1.2 C.0.9 D.0.83

Q14

The electric potential of an electron is given by \(V = V_0 \ln\left(\frac{r}{r_0}\right)\), where \(r_0\) is a constant. If Bohr atom model is valid, then variation of radius of \(n^{th}\) orbit \(r_n\) with the principal quantum number n is :

A.\(r_n \propto \frac{1}{n^2}\) B.\(r_n \propto \frac{1}{n}\) C.\(r_n \propto n^2\) D.\(r_n \propto n\)

Q15

Transverse nature of light is shown in :

A.scattering B.interference C.polarisation D.diffraction

12th Standard Physics May 2022: Online Practice Test

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