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

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

In case of linearly polarised light, the magnitude of the electric field vector

• does not change with time

• varies periodically with time

• increases and decreases linearly with time

• is parallel to the direction of propagation

Assertion:  The true geographic north direction is found by using a compass needle.

Reason: The impurities meridian of the earth is along the axis of rotation of the earth.

• 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: There are very small sporadic changes in the period of rotation of the earth. 

Reason: Shi fling of large air masses in the earth's atmosphere produce a change in the moment of inertia of the earth causing its period of rotation to 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

76.

The maximum distance upto which TV transmission from a TV of height h can be received is proportional to

• h^1/2

• h

• h³

• h²

In short wave communication, waves of which of the following frequencies will be reflected back by the ionospheric layer having electron density 10¹¹ per  m³ ?

• 2 MHz

• 10 MHz

• 12 MHz

• 18 MHz

X-ray beam are affected by

• electric field

• magnetic field

• both (a) and (b)

• none of these

All components of the electromagnetic spectrum in vacuum have the same

• energy

• velocity

• wavelength

• frequency

The difference between soft and hard X-rays is of :

• velocity

• intensity

• frequency

• polarization