The refractive indices of glass and water with respect to air are 3/2 and 4/3 respectively. If speed of light in glass is 2 × 10⁸ m/s, find the speed of light in water.

Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be:

An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be

The refractive index of a medium V with respect to a medium ‘y’ is 2/3 and the refractive index of medium ‘y’ with respect to medium ‘z’ is 4/3. Find the refractive index of medium ‘z with respect to medium V. If the speed of light in medium ‘x’ is 3 × 10⁸ m s^-1, calculate the speed of light in medium ‘y’.

When a 4 V battery is connected across an unknown resistor there is a current of 100 mA in the circuit. The value of the resistance of the resistor is:

A boy records that 4000 joules of work is required to transfer 10 coulombs of charge between two points of a resistor of 50 Ω. The current passing through it is _____.

A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with each other. Calculate the lens power of this combination.

An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focussed image can be obtained ? Find the size and the nature of the image.

An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed.

A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens ? Draw the ray diagram.

A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object ? Also, find the power of the lens

Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass

Find the focal length of a lens of power -2.0 D. What type of lens is this ?

An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position of the image, its nature and size.

A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located ?

calculate effective resistance across X&Y

Two lamps, one rated 100 W at 220 V and the other 200 W at 220 V are connected (i) in series and (ii) in parallel to the electric main supply of 220 V. Find the current drawn in each case.

A person needs a lens of power –4.5 D for correction of her vision.
(a) What kind of defect in vision is she suffering from?
(b) What is the focal length of the corrective lens?
(c) What is the nature of the corrective lens?