Let C be the capacitance of a capacitor discharging through a resistor R. Suppose t1 is the time taken for the energy stored in the capacitor to reduce to half its initial value and t2 is the time taken for the charge to reduce to one-fourth its initial value. Then what will be the ratio t1/t2

Anonymous User Physics Electromagnetic Induction & Alternating Current 11 May, 2020 1 Answer 54 views

The masses of neutron and proton are 1.0087 amu and 1.0073 amu respectively. If a helium nucleus (alpha particles) of mass 4.0015 amu is formed by combining neutrons and protons. The binding energy of the helium nucleus will be (1 amu = 931 MeV)

Anonymous User Physics Nuclear physics 11 May, 2020 1 Answer 56 views




In a series LCR circuit R = 200  and the voltage and the frequency of the main supply is 220 V and 50 Hz respectively. On taking out the capacitance from the circuit the current lags behind the voltage by 30°. On taking out the inductor from the circuit the current leads the voltage by 30°. The power dissipated in the LCR circuit is

Anonymous User Physics Electromagnetic Induction & Alternating Current 11 May, 2020 1 Answer 58 views

Let there be a spherically symmetric charge distribution with charge density varying as upto r = R, and r(r) = 0 for r > R, where r is the distance from the origin. The electric field at a distance r (r < R) from the origin is given by

Anonymous User Physics Electrostatic 11 May, 2020 1 Answer 53 views




20 g of non-electrolyte, non-volatile solute (CxH2xOx), when dissolved in 100 gm water at 100°C, lowers the vapour pressure of solution by 1/100 th of the vapour pressure of pure water at this temperature. What is formula of the compound?

Anonymous User Chemistry Solutions 11 May, 2020 1 Answer 106 views









A nucleus of mass M + ∆m is at rest and decays into two daughter nuclei of equal mass M / 2 each. Speed of light is c.

The binding energy per nucleon for the parent nucleus is E1 and that for the daughter nuclei is E2. Then

Anonymous User Physics Atomic Physics 10 May, 2020 1 Answer 56 views

An initially parallel cylindrical beam travels in a medium of refractive index  where  and  are positive constants and I is the intensity of the light beam. The intensity of the beam is decreasing with increasing radius.

 What will be the initial shape of the wavefront of the beam?

Anonymous User Physics Wave Optics 10 May, 2020 1 Answer 54 views

An initially parallel cylindrical beam travels in a medium of refractive index  where  and  are positive constants and I is the intensity of the light beam. The intensity of the beam is decreasing with increasing radius.

What will be the speed of light in the medium?

Anonymous User Physics Wave Optics 10 May, 2020 1 Answer 57 views

An initially parallel cylindrical beam travels in a medium of refractive index  where  and  are positive constants and I is the intensity of the light beam. The intensity of the beam is decreasing with increasing radius.

As the beam enters the medium, it will

Anonymous User Physics Wave Optics 10 May, 2020 1 Answer 54 views

A transparent solid cylindrical rod has a refractive index of . It is surrounded by air. A light ray is incident at the mid-point of one end of the rod as shown in the figure

The incident angle θ for which the light ray grazes along the wall of the rod is

Anonymous User Physics Ray Optics 09 May, 2020 1 Answer 59 views

A long metallic bar is carrying heat from one of its ends to the other end under steady-state. The variation of temperature θ along the length x of the bar from its hot end is best described by which of the figures?

Anonymous User Physics Heat Transfer 09 May, 2020 1 Answer 54 views


Consider a rubber ball freely falling from a height h = 4.9 m onto a horizontal elastic plate. Assume that the duration of collision is negligible and the collision with the plate is totally elastic. Then what will be the velocity as a function of time and the height as function of time? 

Anonymous User Physics Work Power and Energy 09 May, 2020 1 Answer 63 views

A motor cycle starts from rest and accelerates along a straight path at 2 m/s2. At the starting point of the motor cycle there is a stationary electric siren. How far has the motor cycle gone when the driver hears the frequency of the siren at 94% of its value when the motor cycle was at rest? (Speed of sound = 330 ms-1).

Anonymous User Physics Work Power and Energy 09 May, 2020 1 Answer 56 views






An inductor of inductance L = 400 mH and resistors of resistances R1 = 2  and R2 = 2  are connected to a battery of emf 12 V as shown in the figure. The internal resistance of the battery is negligible. The switch S is closed at t = 0. What will be the potential drop across L as a function of time?

Anonymous User Physics Electromagnetic Induction & Alternating Current 09 May, 2020 1 Answer 64 views

In an experiment the angles are required to be measured using an instrument. 29 divisions of the main scale exactly coincide with the 30 divisions of the vernier scale. If the smallest division of the main scale is half-a-degree (= 0.5°), then the least count of the instrument will be 

Anonymous User Physics 09 May, 2020 1 Answer 55 views

Two wires are made of the same material and have the same volume. However wire 1 has cross-sectional area A and wire 2 has cross-sectional area 3A. If the length of wire 1 increases by ∆x on applying force F, how much force is needed to stretch wire 2 by the same amount?

Anonymous User Physics 09 May, 2020 1 Answer 55 views





Two identical glass rods S1 and S2 (refractive index = 1.5) have one convex end of radius of curvature 10 cm. They are placed with the curved surfaces at a distance d as shown in the figure, with their axes (shown by the dashed line) aligned. When a point source of light P is placed inside rod S1 on its axis at a distance of 50 cm from the curved face, the light rays emanating from it are found to be parallel to the axis inside S2.The distance d is

Ray optics

Anonymous User Physics Ray Optics 08 May, 2020 1 Answer 60 views

A point source S is placed at the bottom of a transparent block of height 10 mm and refractive index 2.72. It is immersed in a lower refractive index liquid as shown in the figure. It is found that the light emerging from the block to the liquid forms a circular bright spot of diameter 11.54 mm on the top of the block. The refractive index of the liquid is?

A point source S is placed at the bottom of a transparent block of height 10 mm and refractive index 2.72. It is immersed in a lower refractive index liquid as shown in the figure. It is found that the light emerging from the block to the liquid forms a circular bright spot of diameter 11.54 mm on the top of the block. The refractive index of the liquid is?

Anonymous User Physics Ray Optics 08 May, 2020 1 Answer 60 views


A bi-convex lens is formed with two thin plano convex lenses. Refractive index n of the first lens is 1.5 and that of the second lens is 1.2. Both the curved surfaces are of the same radius of curvature R = 14 cm. For this bi-convex lens, for an object distance of 40 cm, the image distance will be.

Anonymous User Physics Ray Optics 08 May, 2020 1 Answer 57 views

The image of an object, formed by a plano-convex lens at a distance of 8 m behind the lens, is real is one-third the size of the object. The wavelength of light inside the lens is 3 times the wavelength in free space.The radius of the curved surface of the lens is

Anonymous User Physics Ray Optics 08 May, 2020 1 Answer 59 views