When a body is placed in surroundings at a constant temperature of 20°C, and heated by a 10-W heater, its temperature remains constant at 40°C. If the temperature of the body is now raised from 20°C to 80°C in 5 minutes at a uniform rate, the total heat it will lose to the surroundings will be-

In the given figure flux through surface S₁ is ϕ₁ &  through S₂ is ϕ₂. Which is correct ?

Three concentric spherical conducting shells having radii R, 2R and 3R are shown in figure. Charge on inner most sphere after it is earthed is : 

Given circuit represents an ammeter. Resistance of each Galvanometer coil is 100Ω and shows maximum deflection at 10mA current. Range of ammeter is

Amount of heat produced in 8Ω resistor after key is closed is : 

A 100 turn closely wound circular coil of radius 10 cm carries a current of 3.2 A. The coil is placed in a vertical plane and is free to rotate about a horizontal axis which coincides with its diameter. A uniform magnetic field of 2T in the horizontal direction exists such that initially the axis of the coil is in the direction of the field. What is the approximate angular speed aquired by the coil when it has rotated by 90°? The moment of inertia of the coil about given diameter is 0.1 kg m².

A square conducting loop is placed in the time varying magnetic field (db/dt = -ve constant).  The centre of square coincides with axis of cylindrical region of magnetic field. The directions of induced electric field at point a, b and c.

A concave mirror of radius h is placed at the bottom of a tank containing a liquid of refractive index µ upto a depth d. An object P is placed at height 2h above the bottom of the mirror. Outside the liquid, an observer O views the object and its image in the mirror. The apparent distance between these two will be:- [d > 2h]

A radio nuclide A₁ with decay constant λ₁ transforms into a radio nuclide A₂ with decay constant λ₂. At the initial moment the preparation contained only the radio nuclide A₁. The time interval after which the activity of radio nuclide A₂ reaches its maximum value is (λ₂ > λ₁) :- 

In  a  YDSE  experiment λ = 540 nm, D = 1m, d = 1 mm. A thin film is pasted on upper slit and the central maxima shifts to the point just in front of the upper slit. What is the path difference at the centre of the screen ?