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If the angular velocity of earth’s spin is increased such that the bodies at the equator start floating, the duration of the day would be approximately

If the angular velocity of earth's spin is increased such that the bodies at the equator start floating, the duration of the day would be... View Article

The speed of electrons in a scanning electron microscope is 1×10⁷ ms^-1.

The speed of electrons in a scanning electron microscope is 1×107 ms-1. If the protons having the same speed are used instead of electrons,... View Article

Which of the following statements are correct ?

Which of the following statements are correct ? (A) Electric monopoles do not exist whereas magnetic monopoles exist. (B) Magnetic field lines... View Article

A particle of mass m moves in a circular orbit under the central potential field

A particle of mass m moves in a circular orbit under the central potential field, U(r)= -C/r, where C is a positive constant. The correct radius... View Article

Consider a sample of oxygen behaving like an ideal gas. At 300 K, the ratio of root mean square (rms) velocity to the average velocity of gas molecule would be : (Molecular weight of oxygen is 32 g/mol; R=8.3 JK^-1mol^-1)

a. b. c. d. Answer: (c) And Therefore,... View Article

Three rays of light, namely red (R), green (G) and blue (B) are incident on the face PQ of a right angled prism PQR as shown in the figure.

Three rays of light, namely red (R), green (G) and blue (B) are incident on the face PQ of a right angled prism PQR as shown in the figure.... View Article

The velocity – displacement graph of a particle is shown in the figure.

The velocity – displacement graph of a particle is shown in the figure. The acceleration – displacement graph of the same particle... View Article

The angular momentum of a planet of mass M moving around the sun in an elliptical orbit is [latex]vec{L}[/latex]. The magnitude of the areal velocity of the planet is

a. L/M b. 2L/M c. L/2M d. 4L/M Answer: (c) Theoretical concept. ∴ Areal velocity, dA/dt=L/2M → L = Angular momentum of planet... View Article

Consider a uniform wire of mass M and length L. It is bent into a semicircle. Its moment of inertia about a line perpendicular to the plane of the wire passing through the centre is

a. b. c. d. Answer: (d) ∵ L=πR ⇒R=L/π & moment of inertia = MR2 = M(L/π)2=ML2/π2... View Article

The function of time representing a simple harmonic motion with a period of π/ω is

a. cos(ωt) + cos(2ωt) + cos(3ωt) b. 3cos(π/4-2ωt) c. sin2(ωt) d. sin(ωt) + cos(ωt) Answer: (b)... View Article

A proton and an α-particle, having kinetic energies K_p and K_α respectively, enter into a magnetic field at right angles.

A proton and an α-particle, having kinetic energies Kp and Kα respectively, enter into a magnetic field at right angles. The ratio of... View Article

In a series LCR circuit, the inductive reactance (X_L) is 10 Ω and the capacitive reactance (X_C) is 4 Ω. The resistance (R) in the circuit is 6 Ω. Find the power factor of the circuit.

a. b. c. ½ d. Answer: (a) Given : XL = 10 Ω XC = 4 Ω R = 6 Ω Therefore,... View Article

The correct relation between α (ratio of collector current to emitter current) and β (ratio of collector current to base current) of a transistor is

a. b. c. d. Answer: (a) Since, IE = IB + IC Therefore,... View Article

For an adiabatic expansion of an ideal gas, the fractional change in its pressure is equal to (where λ is the ratio of specific heats)

a. b. dV/V c. d. Answer: (a) For adiabatic expansion : PVγ=const. ⇒lnP+γlnV=const. ⇒ differentiating both... View Article

The time taken for the magnetic energy to reach 25% of its maximum value, when a solenoid of resistance R, inductance L is connected to a battery, is

a. (L/R)ln2 b. (L/R)ln10 c. Infinite d. (L/R)ln5 Answer: (a) Magnetic energy, U=(½)LI2, when the current in the circuit is I. → When... View Article

An ideal gas in a cylinder is separated by a piston in such a way that the entropy of one part is S₁ and that of the other part is S₂. Given that S₁ > S₂. If the piston is removed then the total entropy of the system will be:

a. S1 + S2 b. S1 - S2 c. S1 × S2 d. S1/S2 Answer: (a) for gas 1 , S1= (f/2n1R) for gas 2, S2=(f/2n2R} identical gas, so f will be... View Article

A solid cylinder of mass m is wrapped with an inextensible light string and is placed on a rough inclined plane as shown in the figure.

A solid cylinder of mass m is wrapped with an inextensible light string and is placed on a rough inclined plane as shown in the figure. The... View Article

A plane electromagnetic wave propagating along y-direction can have the following pair of electric field ([latex]vec{E}[/latex] )and magnetic field ([latex]vec{B}[/latex]) components

a. Ex, Bz or Ez, Bx b. Ey, Bx or Ex, By c. Ex, By or Ey, Bx d. Ey, By or Ez, Bz Answer: (a) Therefore, for electromagnetic waves... View Article

An object of mass m₁ collides with another object of mass m₂, which is at rest.

An object of mass m1 collides with another object of mass m2, which is at rest. After the collision, the objects move at equal speeds in opposite... View Article

The decay of a proton to neutron is

a. Not possible as proton mass is less than the neutron mass b. Always possible as it is associated only with β+ decay c. Possible only... View Article

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