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An object at a distance of 20m from a convex lens of focal length 0.3m. The lens forms an image of the object. If the object moves away from the lens at a speed of 5m/s, the speed and direction of the image will be

a. 3.22 × 10–3 m/s towards the lens b. 2.26 × 10–3 m/s away from the lens c. 1.16 × 10–3 m/s towards the lens d. 0.92 × 10–3 m/s away from the... View Article

An electromagnetic wave of intensity 50 Wm^-2 enters in a medium of refractive index ‘n’ without any loss. The ratio of the magnitudes of electric fields, and the ratio of the magnitudes of magnetic fields of the wave before and after entering into the medium are respectively, given by

a. b. c. d. Answer: (b) (For transparent medium ) Therefore, Similarly,... View Article

In the below given circuit the switch S₁ is closed at time t = 0 and the switch S₂ is kept open. At some later time (t₀), the switch S₁ is opened and S₂ is closed. The behavior of the current I as a function of time ‘t’ is given by:

Answer: (2) From time t = 0 to t = t0, growth of current takes place and after that decay of current takes place.... View Article

There are two long co-axial solenoids of same length l. the inner and outer coils have radii r₁ and r₂ and number of turns per unit length n₁ and n₂ respectively. The ratio of mutual inductance to the self-inductance of the inner-coil is:

a. b. c. d. Answer: (d) Mutual Inductance= Self Inductance = Ratio = n2/n1... View Article

In an experiment, electrons are accelerated, from rest, by applying a voltage of 500 V.

Calculate the radius of the path if a magnetic field 100 mT is then applied. [Charge of the electron = 1.6 × 10-19 C Mass of the electron = 9.1... View Article

In a Wheatstone bridge (see fig.), resistances P and Q are approximately equal. When R = 400 Ω, the bridge is equal. When R = 400 Ω, the bridge is balanced. On inter-changing P and Q, the value of R, for balance, is 405 Ω. The value of X is close to

a. 403.5 ohm b. 404.5 ohm c. 401.5 ohm d. 402.5 ohm Answer: (d) Initially -----------(1) After interchanging P and Q -----------(2)... View Article

Two equal resistance when connected in series to a batter, consume electric power of 60 W. If these resistances are now connected in parallel combination to the same battery, the electric power consumed will be:

a. 60 W b. 240 W c. 30 W d. 120 W Answer: (b) In series condition, equivalent resistance is 2R thus power consumed is 60W P =60 =... View Article

The given graph shows variation (with distance r from centre) of:

a. Potential of a uniformly charged sphere b. Potential of a uniformly charged spherical shell c. Electric field of uniformly charged... View Article

Three charges Q +q and +q are placed at the vertices of a right-angle isosceles triangle as shown below. The net electrostatic energy of the configuration is zero, if the value of Q is

a. b. c. -2q d. +q Answer: (b) Net electrostatic energy of the configuration will be Here, Putting ,U =0 we get,... View Article

In the figure shown below, the charge on the left plate of the [latex]10mu F[/latex] capacitor is [latex]-30mu C[/latex]. The charge on the right plate of the 6 [latex]6mu F[/latex] capacitor is:

a. b. c. d. Answer: (d) 6μF & 4μF are in parallel & total charge on this combination is 30 μC Charge on 6μF capacitor =... View Article

Equation of travelling wave on a stretched string of linear density 5 g/m is y = 0.03 sin (450 t – 9x) where distance and time are measured is SI units. The tension in the string is:
a. 12.5 N b. 7.5 N c. 10 N d. 5 N Answer: (a) y = 0.03 sin(450 t – 9x) m/s T = 12.5 N... View Article

A particle undergoing simple harmonic motion has time dependent displacement given by [latex]x(t)=Asinfrac{pi t}{90}[/latex].The ratio of kinetic to potential energy of this particle at t = 210 s will be
a. 1 b. 3 c. 1/9 d. 2 Answer: (b) Hence ratio is 3... View Article

A rigid diatomic ideal gas undergoes an adiabatic process at room temperature. The relation between temperature and volume of this process is TV^X= constant, then x is:
a. (5/3) b. (2/5) c. (2/3) d. (3/5) Answer: (b) Diatomic gas r=1 + (2/5) = 7/5 x=r-1 = (7/5) -1 = 2/5... View Article

Ice at –20° C is added to 50 g of water at 40°C.When the temperature of the mixture reaches 0°C, it is found that 20 g of ice is still not melted. The amount of ice added to the water was close to
(Specific heat of water = 4.2 J/g/°C) Specific heat of Ice = 2.1 J/g/°C Heat of fusion of water at 0°C = 334 J/g) a. 50 g b. 40 g c.... View Article

A satellite is revolving in a circular orbit at a height h from the earth surface, such that h << R where R is the radius of the earth. Assuming that the effect of earth’s atmosphere can be neglected the minimum increase in the speed required so that the satellite could escape from the gravitational field of earth is:
a. b. c. d. Answer: (c)... View Article

An equilateral triangle ABC is cut from a thin solid sheet of wood. (see figure) D, E and F are the mid-points of its sides as shown and G is the centre of the triangle. The moment of inertia of the triangle about an axis passing through G and perpendicular to the plane of the triangle is I₀. It the smaller triangle DEF is removed from ABC, the moment of inertia of the remaining figure about the same axis is I. Then:
a. b. c. d. Answer: (d) Suppose M is mass and a is side of large triangle, then M/4 and a/2 will be mass and side length of... View Article

A slab is subjected to two forces [latex]vec{F_{1}}[/latex] and [latex]vec{F_{2}}[/latex] of same magnitude F as shown in the figure. Force [latex]vec{F_{2}}[/latex]is in XY-plane while force F₁ acts along z-axis at the point [latex](2vec{i}+3vec{j})[/latex]. The moment of these forces about point O will be:
a. b. c. d. Answer: (d) Torque for F1 force... View Article

A body of mass 1 kg falls freely from a height of 100 m on a platform of mass 3 kg which is mounted on a spring having spring constant k = 1.25 × 10⁶ N/m. The body sticks to the platform and the spring’s maximum compression is found to be x. Given that g = 10 ms^–2, the value of x will be close to:
a. 4 cm b. 8 cm c. 80 cm d. 40 cm Answer: (a) Velocity of 1 kg block just before it collides with 3kg block = Applying momentum... View Article

A liquid of density [latex]rho[/latex] is coming out of a hose pipe of radius a with horizontal speed v and hits a mesh. 50% of the liquid passes through the mesh unaffected. 25% looses all of its momentum and 25% comes back with the same speed. The resultant pressure on the mesh will be:
a. b. c. d. Answer: (b) Momentum per second carried by liquid per second is net force due to reflected liquid = net force... View Article

A body is projected at t = 0 with a velocity 10 ms^–1 at an angle of 60° with the horizontal. The radius of curvature of its trajectory at t = 1s is R. Neglecting air resistance and takin acceleration due to gravity g = 10 ms^–2, the value of R is :
a. 2.5 m b. 10.3 m c. 2.8 m d. 5.1 m Answer: (c) vx = 10cos60° = 5 m/s vy = 10cos30° = m/s velocity after t = 1 sec. ... View Article

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