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A particle is thrown vertically upwards. The correct graph between its speed (v) and time (t) is given by (neglecting air resistance).

a) b) c) d) Solution: Option d) is the right answer. This graph explains that when the particle is moving upward, gravity (g) acts on it as a... View Article

In the shown circuit the resistance R can be varied. In which of the option, the variation of the current i against R is correctly plotted?

a) b) c) d) Solution: C) is the right option. Applying Kirchoff's law in the circuit we get, Hence, V-E=0 The current through R... View Article

Figure shows an arrangement of blocks, pulleys, and strings. Strings are massless and frictionless. The relation between acceleration of the blocks as shown in the figure is

A. a_{1}=6a_{2} B. a_{1}=3a_{2} C. a_{2}=6a_{1} D. a_{2}=3a_{1} Solution: C. a_{2}=6a_{1} ... View Article

The switch in circuit shifts from 1 to 2 when Vc > 2V/3 and goes back to 1 from 2 when Vc < V/3. The voltmeter reads voltage as plotted. What is the period T of the wave from in terms of R and C?

a) RCln3 b) RC/2 ln3 c) 2RCln2 d) RC/3 ln3 Solution:a) RCln3... View Article

The circuit diagram shown here corresponds to the logic gate

a) AND b) OR c) NOR d) NAND Solution: c) NOR... View Article

For the given transistor circuit VBE = 0.7 V. Find I :- (1) 3.7 mA (2) 2.2 mA (3) 1.8 mA (4) 1.5 mA 54.

Given VBE = 0.7 V, S=0.7V, and I=2K\Omega I_{E}= \frac{4.3}{2*10^{3}} = 3.7 mA... View Article

In an adiabatic process [latex]1 m^{3}[/latex] of an ideal monatomic gas expands to [latex]8 m^{3}[/latex]. What is the ratio of final to initial temperature?

a) ¼ b) ⅛ c) 1 d) 8 Solution: b) ⅛... View Article

The magnitude of the gravitational field at distance r1 and r2 from the centre of a uniform sphere of radius R and mass M are F1 and F2 respectively, then

Solution: We know that When r1<R, r2<R... View Article

An axle or truck is 2.5 m long. If the truck is moving due North at ms−1 at a place where the vertical component of the earth’s magnetic field is 90 μT, the potential difference between the two ends of the axle is

a) 6.75 mV with North end positive b) 6.75 mV with West end positive c) 6.75 mV with South end positive d) 6.75 mV with East end positive... View Article

A conducting rod of length 2l is rotating with constant angular speed ω about its perpendicular bisector. A uniform magnetic field vec{B} exists parallel to the axis of rotation. The e.m.f., induced between two ends of the rod is

a) Zero b) Solution: a) Zero... View Article

A choke coil is needed to operate an arc lamp at 160V (rms) and 50Hz. The arc lamp has an effective resistance of 5Ω when running at 10A (rms). Calculate the inductance of the choke coil. If the same arc lamp is to be operated on 160V DC, what additional resistance would be required. Compare the power losses in both the cases.

Solution: Let R_{A} be the additional resistance required for operating the arc lamp with 160V DC source, then AC power consumed by the... View Article

An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?

a) The electron will continue to move with uniform velocity along the axis of the solenoid. b) The electron will be accelerated along the axis.... View Article

The peak value of AC is 2sqrt{2} ampere. It’s apparent value will be? – Physics Q&A

a) 0 b) 1 Ampere c) 2 Ampere d) 3 Ampere <strong>Solution:</strong>c) 2 Ampere Explanation: Apparent value is given by the formula:... View Article

The force required to stretch a spring varies with the distance as shown in the figure. If the experiment is performed with the above spring of half the length, the line OA will:-

a) Shift towards F−axis b) Shift towards X−axis c) Remains as it is d) Become double in length Solution: a) Shift towards... View Article

The mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If, for an n-type semiconductor, the density of electrons is 10^{19} m^{-3} and their mobility is 1.6 m^{2}/V.s then the resistivity of the semiconductor (since it is an n-type semiconductor contribution of holes is ignored) is close to:

Solution: = =... View Article

Two identical cylindrical vessels, with their bases at the same level, each contain a liquid of density ρ. The height of liquid in one vessel in h1 and that in the other is h2. The area of either base is A. What is the work done by gravity in equalising the levels when the vessels are interconnected?

Solution: Refer the figure and assume that the height is h h= Mass of liquid would be equal to m = A The work done equal to h =... View Article

Specific rotation of the sugar solution is 0.01 SI units. 200 kgm−3 of impure sugar solution is taken in a polarimeter tube of length 0.25 m and an optical rotation of 0.4 rad is observed. The percentage of purity of sugar is the sample is

Solution: 2. 80% Explanation: Specific rotation Now percentage purity of sugar solution... View Article

If n, e, τ, m, are representing electron density charge, relaxation time and mass of an electron respectively then the resistance of wire of length l and cross sectional area A is given by

a) ml/ne2rA b) 2mA/ne2r c) ne2rA d) ne2rA/2m Answer:a) ml/ne2rA Solution: Relaxation time, τ = m/ne2ρ ⇒ ρ... View Article

The motion of a particle is defined by the equations x= 4t² and y= 2t³ in metre, where t is in seconds. Determine the normal and tangential components of the particle’s velocity and acceleration when t = 2 s.

Solution: Here, r = (4t2)i + (2t3)j v = dr/dt = (8t)i + (6t2)j when t = 2 s, v = (8 x 2)i + (6 x 22)j = 16i + 24j Then, v... View Article

A swimmer can swim in still water at 1.5 ms^–1. The river is flowing with 2 ms^–1 from left to right. The minimum time taken by swimmer to cross the river and the drift in that case are respectively

a) (20/9) minute, (800/3) m b) (10/9) minute, (400/3) m c) (40/9) minute, (200/3) m d) (5/3) minute, 200 m Answer: a) (20/9) minute, (800/3)... View Article

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