JEE Main entrance exam Question Bank Solutions for Physics (JEE Main)

The height of mercury column measured with brass scale at temperature T₀ is H₀. What height H' will the mercury column have at T = 0°C. Coefficient of volume expansion of mercury is γ. Coefficient of linear expansion of brass is α ______.

An anisotropic material has coefficient of linear thermal expansion α₁, α₂ and α₃ along x, y and z-axis respectively. Coefficient of cubical expansion of its material will be equal to ______.

A parallel plate capacitor filled with a medium of dielectric constant 10, is connected across a battery and is charged. The dielectric slab is replaced by another slab of dielectric constant 15. Then the energy of capacitor will  ______.

Length of steel rod so that it is 5 cm longer than the copper rod at all temperatures should be ______ cm.

(α for copper = 1.7 × 10^-5/°C and α for steel = 1.1 × 10^-5/°C)

A metal ball immersed in water weighs w₁ at 0°C and w₂ at 50°C. The coefficient of cubical expansion of metal is less than that of water. Then ______.

A disc is rotating freely about its axis. The percentage change in angular velocity of a disc if temperature decreases by 20°C is ______.

(coefficient of linear expansion of material of disc is 5 × 10^-4/°C)

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

• Assertion A: When a rod lying freely is heated, no thermal stress is developed in it.
• Reason R: On heating, the length of the rod increases. In light of the above statements.

choose the correct answer from the options given below:

If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously will be ______.

A plane mirror is moving with velocity `4hati + 5hatj + 8hatk`. A point object in front of the mirror moves with a velocity of `3hati + 4hatj + 5hatk`. Here `hatk` is along the normal to the plane mirror and facing toward the object. The velocity of the image is ______.

If two plane mirrors are kept at 60° to each other, then the number of images formed by them is ______.

A block of ice of mass 120 g at temperature 0°C is put in 300 gm of water at 25°C. The xg of ice melts as the temperature of the water reaches 0°C. The value of x is ______.

[Use: Specific heat capacity of water = 4200 Jkg^-1K^-1, Latent heat of ice = 3.5 × 10⁵ Jkg^-1]

A geyser heats water flowing at a rate of 2.0 kg per minute from 30°C to 70°C. If the geyser operates on a gas burner, the rate of combustion of fuel will be ______ g min^-1.

[Heat of combustion = 8 × 10³ Jg^-1 Specific heat of water = 4.2 Jg^-1°C^-1]

On an X temperature scale, water freezes at -125°X and boils at 375°X. On a Y temperature scale, water freezes at -70°Y and boils at -30°Y. The value of temperature on X scale is ______ on which value of temperature on y Scale becomes 50° Y.

A copper block of mass 2.5 kg is heated in a furnace to a temperature of 500°C and then placed on large ice block. The maximum amount of ice that can melt is ______.

(Specific heat of copper = 0.39 Jg^-1 c^-1, latent heat of 0 fusion of water = 335 Jg^-1)

80 gm of water at 30°C is poured on a large block of ice at 0°C. The mass of ice that melts is ______.

Work done in converting one gram of ice at -10°C into steam at 100°C is ______.

The specific heat of a substance is given by C = a + bT, where a = 1.12 kJ kg^-1K^-1 and b = 0.016 kJ-kg K^-2. The amount of heat required to raise the temperature of 1.2 kg of the material from 280 K to 312 K is ______.

A converging lens of focal length f is placed at a distance 0.3 m from an object to produce an image on a screen 0.9 m from the lens. With the object and the screen in the same positions, an image of the object could also be produced on the screen by placing a converging lens of focal length.

In normal adjustment, for a refracting telescope, the distance between objective and eye piece is 30 cm. The focal length of the objective, when the angular magnification of the telescope is 2, will be ______.

500 g of water and 100 g of ice at 0°C are in a calorimeter whose water equivalent is 40 g. 10 g of steam at 100°C is added to it. Then water in the calorimeter is ______.

(Latent heat of ice = 80 cal/g, Latent heat of steam = 540 cal/g)