Explanation

During a thunderstorm, the Earth can have a net positive charge on its surface.

This is because the negatively charged clouds above the Earth induce a positive charge on the Earth's surface.

Explanation

Microwaves are a type of electromagnetic radiation that are used to heat food in microwave ovens.

Microwaves are absorbed by water molecules in food, which increases the kinetic energy of the molecules and heats the food.

Microwaves have several characteristics that make them useful for cooking, including:

• They are reflected by metal
• They can pass through glass, paper, and plastic
• They are absorbed by food

Explanation

Photoelectric effect does not demonstrate the wave nature of light; it shows light behaving as particles (photons).

The phenomena of diffraction, polarization, and interference are clear evidence of light's wave nature.

Explanation

The central layer is made very thin and lightly doped as compared with the two outer layers and is called the base.

The outer sections are called emitter and collector.

Explanation

A black body is both an ideal absorber and an ideal radiator of radiation.

It absorbs all incident radiation perfectly and emits radiation at the maximum possible rate for any given temperature.

Explanation

The product of resistance (R) and capacitance (C), denoted as RC, has dimensions of time.

Explanation

The Compton shift is equal to the Compton wavelength at a scattering angle of 180 degrees.

Explanation

If the third bulb is connected in series with bulbs A and B, the total resistance in the circuit will increase. As a result, the current flowing through the circuit will decrease, leading to a decrease in the brightness of all bulbs.

Explanation

To calculate the focal length of a lens, you can use the formula: P = 1/f

Given that the power of the lens is 10 diopters, we can rearrange the formula to solve for the focal length:

f= 1/p

f= 1/10

f= 0.1m

Since 1 meter = 100 cm, the focal length in centimeters is 0.1m × 100 cm/m= 10cm.

Explanation

If the capacitance C and resistance R of an RC circuit are given, τ= RC is the time constant (τ) of the circuit.