AIPMT 2014 | Electromagnetic Waves Question 18 | Physics

Light with an energy flux of 25 $$ \times $$ 10⁴ W m^$$-$$2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm², the average force exerted on the surface is

1.25 $$ \times $$ 10^$$-$$6 N

2.50 $$ \times $$ 10^$$-$$6 N

1.20 $$ \times $$ 10^$$-$$6 N

3.0 $$ \times $$ 10^$$-$$6 N

NEET 2013 (Karnataka)

MCQ (Single Correct Answer)

-1

An electromagnetic wave of frequency $$\upsilon = 3.0$$ MHz passes from vaccum into a dielectric medium with relative permittivity $${{\varepsilon _r}}$$ = 4.0. Then

Wavelength is doubled and frequency becomes half.

Wavelength is halved and frequency remains unchanged.

Wavelength and frequency both remain unchanged.

Wavelength is doubled and frequency unchanged.

NEET 2013

MCQ (Single Correct Answer)

-1

The condition under which a microwave oven heats up a food item containing water molecules most efficiently is

Microwaves are heat waves, so always produce heating.

Infra-red waves produce heating in a microwave oven.

The frequency of the microwaves must match the resonant frequency of the water molecules.

The frequency of the microwaves has no relation with natural frequency of water molecules.

AIPMT 2012 Mains

MCQ (Single Correct Answer)

-1

The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagatting in vacuum is equal to

the speed of light in vacuum

reciprocal of speed of light in vacuum

the ratio of magnetic permeability to the electric susceptibility of vacuum

unity

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