CBSE
Multiple Choice QuestionsIf there were no atmosphere, the average temperature on earth surface would be
lower
higher
same
0°C
Asserion: : NAND is a universal gate.
Reason: It can be used to describe all other logic gates.
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
Black holes in orbit around a normal star are detected from earth due to the frictional heating of infalling gas into the black hole, which can reach temperatures greater than 106 K. Assuming that the infalling gas can be modelled as a blackbody radiator, then the wavelength of maximum power lies
in the visible region
in the X-ray region
in the microwave region
in the gamma-ray region of electromagnetic spectrum
If vy , vx and vm are the speeds of gamma rays, X-rays and microwaves respectively in vacuum, then
vy > vx > vm
vy < vx < vm
vy > vx > vm
vy = vx = vm
Assertion: Magnetic Resonance Imaging (MRI) is a useful diagnostic tool for producing images of various parts of human body.
Reason: Protons of various tissues of human body play a role in MRI.
If both assertion and reason are true and reason is the correct explanation of the assertion
If both assertion and reason are true but reason is not the correct explanation of the assertion
If assertion is true, but reason is false
Both assertion and reason are false statements
Assertion: Dipole oscillations produce electromagnetic waves.
Reason: Accelerated charge produces electromagnetic waves.
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 velocity of electromagnetic radiation in a medium of permittivity ε0 and permeability μ0 is given by
Assertion: X-rays can penetrate through the flesh but not through the bones.
Reason: The penetrating power of X-rays depends on voltage.
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 wavelength of sun is used finally as electric energy?
Radio waves
Infrared waves
Visible light
visible light
CO2 laser uses
microwaves
infra red
ultra violet
visible light
