CBSE
Multiple Choice QuestionsAssertion: Electromagnetic waves with frequencies smaller than the critical frequencies of ionosphere cannot be used for communication using sky wave propagation.
Reason: The refractive index of the ionosphere becomes very high for frequencies higher than the critical frequency.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Assertion: Electromagnetic radiations exert pressure.
Reason: Electromagnetic-waves carry both momentum and energy.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Assertion: Electromagnetic waves are transverse in nature
Reason: The electric and magnetic fields of an e.m. wave are perpendicular to each other and also perpendicular to the direction of wave propogation.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Assertion: X-ray astronomy is possible only from satellites orbiting the earth.
Reason: Efficiency of X-rays telescope is large as compared to any other telescope.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Which of the following electromagnetic waves have the smallest wavelength?
γ - rays
X- rays
UV waves
infrared rays
Assertion: UV radiation causes photodissociation of ozone into O2 and O, thus causing damage to the stratospheric ozone layer.
Reason: Ozone hole is resulting in global warming and climate change.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false
If both assertion and reason are false
Assertion: In electromagnetic waves electric field and magnetic field lines are perpendicular to each other.
Reason: Electric field and magnetic field are self sustaining.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
The frequency order for X-rays ( A), γ-rays (B), UV rays (C) is
B > A > C
A > B > C
C > B > A
A > C > B
Assertion: The electromagnetic waves are transverse in nature.
Reason: Waves of wavelength 10 µm are radiowave and microwave.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
X-rays are used in determining the molecular structure of crystalline because
its energy is high
it can penetrate the material
its wavelength is comparable to interatomic distance
its frequency is low
