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A short straight object of height 100 cm lies before the central axis of a spherical mirror whose focal length has absolute value |f| = 40 cm. The image of the object produced by the mirror is of height 25 cm and has the same orientation as the object. One may conclude from the information:

a. Image is real, same side of concave mirror b. Image is virtual, opposite side of convex mirror. c. Image is virtual, opposite side of... View Article

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Body 'P' having mass M moving... View Article

Find the electric field E at point P

Find the electric field E at point P (as shown in the figure) on the perpendicular bisector of a uniformly charged thin wire of length L carrying... View Article

Assume that a tunnel is dug along a chord of the earth, at a perpendicular distance (R/2) from the earth’s centre, where ‘R’ is the radius of the Earth. The wall of the tunnel is frictionless. If a particle is released in this tunnel, it will execute a simple harmonic motion with a time period:

a. 2π√R/g b. (1/2π)√(g/R) c. 2πR/g d. g/2πR Answer: (a) cos θ = x/d If displaced from equilibrium position,... View Article

Find the gravitational force of attraction

Find the gravitational force of attraction between the ring and sphere as shown in the diagram, where the plane of the ring is perpendicular to... View Article

Five equal resistances are connected in a network

Five equal resistances are connected in a network as shown in the figure. The net resistance between points A and B is: a. 3R/2 b.... View Article

LED is constructed from Ga-As-P semiconducting material. The energy gap of this LED is 1.9 eV. Calculate the wavelength of light emitted and its colour.

[h = 6.63×10–34 Js and c = 3×108 ms–1] a. 654 nm and red colour b. 1046 nm and blue colour c. 1046 nm and red colour d. 654 nm and orange... View Article

The normal density of a material is ρ and its bulk modulus of elasticity is K. The magnitude of increase in density of material when a pressure P is applied uniformly on all sides, will be:

a. ρK/P b. K/ρP c. PK/ρ d. ρP/K Answer: (d) Bulk modulus K = -P/(ΔV/V) We know, ρ = M/V So, -Δρ/ρ =... View Article

Four identical solid spheres each of mass ‘m’ and radius ‘a’ are placed with their centres on the four corners of a square of side ‘b’. The moment of inertia of the system about one side of square where the axis of rotation is parallel to the plane of the square is:

a. ⅘ ma2 b. (8/5) ma2 + mb2 c. ⅘ ma2 + 2mb2 d. (8/5) ma2 + 2mb2 Answer: (d) I = ⅖ ma2 + ⅖ ma2 + [⅖ ma2+mb2 ]+ [⅖ ma2 + mb2] I = 4 ×(⅖)ma2... View Article

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: An electron microscope can... View Article

In Young’s double-slit experiment two slits are separated by 2 mm and the screen is placed one meter away. When light of wavelength 500 nm is used, the fringe separation will be:

a. 0.75 mm b. 0.50 mm c. 1 mm d. 0.25 mm Answer: (d) Fringe width (β) = λD/d d = 2×10–3 m λ = 500×10–9... View Article

The temperature θ at the junction of two insulating sheets, having thermal resistances R₁ and R₂

The temperature θ at the junction of two insulating sheets, having thermal resistances R1 and R2 as well as the bottom and top temperatures... View Article

If λ₁ and λ₂ are the wavelengths of the third member of Lyman and the first member of the Paschen series respectively, then the value of λ₁ : λ₂ is

a. 1 : 3 b. 1 : 9 c. 7 : 135 d. 7 : 108 Answer: (c) For Lyman series n1 = 1, n2 = 4 1/λ1 = RZ2(1/n12 - 1/n22) 1/λ1 = RZ2(1/12 -... View Article

Time period of a simple pendulum is T

Time period of a simple pendulum is T. The time taken to complete ⅝ oscillations starting from mean position is (α/12)T. The value of... View Article

The volume V of a given mass of monatomic gas changes with temperature T according to the relation V = KT^2/3. The work done when temperature changes by 90 K will be xR. The value of x is ____. [R = universal gas constant]

Answer: 60 Given: V = KT2/3 V3/2 = (K)3/2 T TV–3/2 = const. ……(1) and TV γ-1 = const.……(2) From (1) &... View Article

27 similar drops of mercury are maintained at 10 V each. All these spherical drops combine into a single big drop. The potential energy of the bigger drop is _____ times that of a smaller drop.

Answer: 243 The self - energy of the sphere (conducting) U = kq2/2r For small drop →Ui = kq2/2r …….(1) After combine small... View Article

In the reported figure of the earth, the value of acceleration due to gravity is the same at point A and C but it is smaller than that of its value at point B (surface of the earth). The value of OA: AB will be x: 5. The value of x is _______________.

In the reported figure of the earth, the value of acceleration due to gravity is the same at point A and C but it is smaller than that of its... View Article

The Zener diode has a V_Z= 30 V. The current passing through the diode for the following circuit is______mA.

The Zener diode has a VZ = 30 V. The current passing through the diode for the following circuit is______mA. Answer: 9 I = (90 -... View Article

A point source of light S, placed at a distance 60 cm in front of the centre of the plane mirror of width 50 cm

A point source of light S, placed at a distance 60 cm in front of the centre of the plane mirror of width 50 cm, hangs vertically on a wall. A... View Article

Two streams of photons, possessing energies equal to twice and ten times the work function of metal are incident on the metal surface successively. The value of the ratio of maximum velocities of the photoelectrons emitted in the two respective cases is x : 3. The value of x is ________.

Answer: 1 According to Einstein’s law of PE effect Emax = E - ϕ E1 = 2 ϕ, k1 = ϕ E2 = 10 ϕ, k2 = 9 ϕ ∴V∝√k (k = ½... View Article

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