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Question 14 Marks

A charge is a property associated with the matter due to which it experiences and produces an electric and magnetic field. Charges are scalar in nature and they add up like real numbers. Also, the total charge of an isolated system is always conserved. When the objects rub against each other charges acquired by them must be

(i) The cause of charging is:
(a) the actual transfer of atoms
(b) the actual transfer of protons
(c) the actual transfer of electrons
(d) the actual transfer of neutrons

(ii) Pick the correct statement.
i. The glass rod gives protons to silk when they are rubbed against each other.
ii. The glass rod gives electrons to silk when they are rubbed against each other.
iii. The glass rod gains protons from silk when they are rubbed against each other.
iv. The glass rod gains electrons when they are rubbed against each other.
(a) Option (i) (b) Option (iv) (c) Option (iii) (d) Option (ii)

(iii) If two electrons are each $1.5 \times 10^{-10} m$ from a proton, as shown in Figure, magnitude of the net electric force they will exert on the proton is

(a) $1.97 \times 10^{-8} N$
(b) $3.83 \times 10^{-8} N$
(c) $4.63 \times 10^{-8} N$
(d) $2.73 \times 10^{-8} N$

(iv) A charge is a property associated with the matter due to which it produces and experiences:
(a) electric effects only
(b) magnetic effects only
(c) both electric and magnetic effects
(d) non magnetic effects only

OR

The cause of quantization of electric charges is:
(a) transfer of an integral number of electrons
(b) transfer of an integral number of neutrons
(c) transfer of an integral number of protons
(d) transfer of an integral number of Atom

Answer

A charge is a property associated with the matter due to which it experiences and produces an electric and magnetic field. Charges are scalar in nature and they add up like real numbers. Also, the total charge of an isolated system is always conserved. When the objects rub against each other charges acquired by them must be equal and opposite.

(i) (c) the actual transfer of electrons
Explanation: the actual transfer of electrons

(ii) (d) Option (ii)
Explanation: The glass rod gives electrons to silk when they are rubbed against each other.

(iii) (a) $1.97 \times 10^{-8} N$
Explanation: $1.97 \times 10^{-8} N$

(iv) (c) both electric and magnetic effects
Explanation: both electric and magnetic effects

OR

(a) transfer of an integral number of electrons
Explanation: transfer of an integral number of electrons

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Question 24 Marks

Radio waves are produced by the accelerated motion of charges in conducting wires. Microwaves are produced by special vacuum tubes. Infrared waves are produced by hot bodies and molecules also known as heat waves. UV rays are produced by special lamps and very hot bodies like Sun.

(i) Solar radiation is
i. transverse electromagnetic wave
ii. longitudinal electromagnetic waves
iii. both longitudinal and transverse electromagnetic waves
iv. none of these.
(a) Option (i) (b) Option (iv) (c) Option (iii) (d) Option (ii)

(ii) What is the cause of greenhouse effect?
(a) Ultraviolet rays (b) X-rays (c) Infrared rays (d) Radiowaves

(iii) Biological importance of ozone layer is
(a) it stops ultraviolet rays
(b) none of these.
(c) it reflects radiowaves
(d) It layer reduces greenhouse effect

OR

Earth's atmosphere is richest in
(a) ultraviolet (b) infrared (c) X-rays (d) microwaves

(iv) Ozone is found in
(a) troposphere (b) mesosphere (c) ionosphere (d) stratosphere

Answer

Radio waves are produced by the accelerated motion of charges in conducting wires. Microwaves are produced by special vacuum tubes. Infrared waves are produced by hot bodies and molecules also known as heat waves. UV rays are produced by special lamps and very hot bodies like Sun.

(i) (a) Option (i)
Explanation: transverse electromagnetic wave

(ii) (c) Infrared rays
Explanation: Greenhouse effect is due to infrared rays.

(iii) (a) it stops ultraviolet rays
Explanation: Ozone layer absorbs the harmful ultraviolet radiations coming from the sun.

OR

(b) infrared
Explanation: The atmosphere of earth is richest in infrared radiation.

(iv) (d) stratosphere
Explanation: Ozone layer lies in stratosphere.

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Physics 4 Marks Questions

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