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# CBSE Physics Past year paper (Solutions) - 2017, Class 12 Class 12 Notes | EduRev

## Class 12 : CBSE Physics Past year paper (Solutions) - 2017, Class 12 Class 12 Notes | EduRev

``` Page 1

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

CBSE
Class XII Physics – Set 1
Board Paper – All India – 2017 Solution

SECTION A

1. Nichrome wire is heated more
? ?
22
nichrome copper
nichrome copper
Heat dissipate in a wire is given by
H I Rt I t
A
H I, and A remains same
But
HH
?
??
? ? ?
? ? ?
??

2. Yes. As an electromagnetic wave is a combination of electric and magnetic
fields, it carries both energy and momentum. It is given by
hC
E
p mC
?
?
?

where
c = Speed of EM wave in vacuum
? = Wavelength of EM wave

3. If the incident violet light is replaced with red light, then the angle of minimum
deviation of a glass prism decreases.

4. Photoelectric effect shows the quantum nature of electromagnetic radiation.

5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate
B, i.e. polarity of Plate A will be positive with respect to Plate B.

Page 2

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

CBSE
Class XII Physics – Set 1
Board Paper – All India – 2017 Solution

SECTION A

1. Nichrome wire is heated more
? ?
22
nichrome copper
nichrome copper
Heat dissipate in a wire is given by
H I Rt I t
A
H I, and A remains same
But
HH
?
??
? ? ?
? ? ?
??

2. Yes. As an electromagnetic wave is a combination of electric and magnetic
fields, it carries both energy and momentum. It is given by
hC
E
p mC
?
?
?

where
c = Speed of EM wave in vacuum
? = Wavelength of EM wave

3. If the incident violet light is replaced with red light, then the angle of minimum
deviation of a glass prism decreases.

4. Photoelectric effect shows the quantum nature of electromagnetic radiation.

5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate
B, i.e. polarity of Plate A will be positive with respect to Plate B.

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

SECTION B

6.

Intensity distribution graph for single slit diffraction

Difference between interference pattern and diffraction pattern

Interference Diffraction
It is due to the superposition of two
waves coming from two coherent
sources.
It is due to the superposition of
secondary wavelets originating from
different parts of the same wavefront.
Width of the interference bands is
equal.
Width of diffraction bands is not the
same.

Page 3

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

CBSE
Class XII Physics – Set 1
Board Paper – All India – 2017 Solution

SECTION A

1. Nichrome wire is heated more
? ?
22
nichrome copper
nichrome copper
Heat dissipate in a wire is given by
H I Rt I t
A
H I, and A remains same
But
HH
?
??
? ? ?
? ? ?
??

2. Yes. As an electromagnetic wave is a combination of electric and magnetic
fields, it carries both energy and momentum. It is given by
hC
E
p mC
?
?
?

where
c = Speed of EM wave in vacuum
? = Wavelength of EM wave

3. If the incident violet light is replaced with red light, then the angle of minimum
deviation of a glass prism decreases.

4. Photoelectric effect shows the quantum nature of electromagnetic radiation.

5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate
B, i.e. polarity of Plate A will be positive with respect to Plate B.

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

SECTION B

6.

Intensity distribution graph for single slit diffraction

Difference between interference pattern and diffraction pattern

Interference Diffraction
It is due to the superposition of two
waves coming from two coherent
sources.
It is due to the superposition of
secondary wavelets originating from
different parts of the same wavefront.
Width of the interference bands is
equal.
Width of diffraction bands is not the
same.

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

OR

According to law of Malus, when a beam of completely plane polarised light is
incident on an analyser ?, resultant intensity of light (I) transmitted from the
analyser varies directly as the square of cosine of angle between the plane of the
analyser and polariser.
? ?
? ?
? ?
? ?
2
2
o
o
I cos
I I cos ........ Equation 1
When 0 or 180
cos 1
I I ........ Equation 2
When 90
c
polarizer and anal
os cos90 0
yzer and parallel
In unpolarised light,
I 0 ........ Equati
vib
on 3
??
? ? ?
? ? ? ? ? ?
? ? ?
??
? ? ?
??
?
??
??
?
? ?
2
av
2
0
2
2
0
rations are probable in all the
direction in a plane perpendicular to the direction of propa

cos
gation
cos
1 cos2

2
.
can have any value from 0 and 2 .
1
d
2
1
2

d
?
?
?
? ? ?
??
??
?? ??
??
?
?
?
?
?
?
? ?
2
0
2
o
o
o
sin2
0
2

1
22
1
2
Using the law of malu

I I cos
s
1
2
I
I
2
I
?
?? ?
?
??
??
??
??
? ? ?
?
??
?
?

Graph:

Page 4

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

CBSE
Class XII Physics – Set 1
Board Paper – All India – 2017 Solution

SECTION A

1. Nichrome wire is heated more
? ?
22
nichrome copper
nichrome copper
Heat dissipate in a wire is given by
H I Rt I t
A
H I, and A remains same
But
HH
?
??
? ? ?
? ? ?
??

2. Yes. As an electromagnetic wave is a combination of electric and magnetic
fields, it carries both energy and momentum. It is given by
hC
E
p mC
?
?
?

where
c = Speed of EM wave in vacuum
? = Wavelength of EM wave

3. If the incident violet light is replaced with red light, then the angle of minimum
deviation of a glass prism decreases.

4. Photoelectric effect shows the quantum nature of electromagnetic radiation.

5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate
B, i.e. polarity of Plate A will be positive with respect to Plate B.

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

SECTION B

6.

Intensity distribution graph for single slit diffraction

Difference between interference pattern and diffraction pattern

Interference Diffraction
It is due to the superposition of two
waves coming from two coherent
sources.
It is due to the superposition of
secondary wavelets originating from
different parts of the same wavefront.
Width of the interference bands is
equal.
Width of diffraction bands is not the
same.

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

OR

According to law of Malus, when a beam of completely plane polarised light is
incident on an analyser ?, resultant intensity of light (I) transmitted from the
analyser varies directly as the square of cosine of angle between the plane of the
analyser and polariser.
? ?
? ?
? ?
? ?
2
2
o
o
I cos
I I cos ........ Equation 1
When 0 or 180
cos 1
I I ........ Equation 2
When 90
c
polarizer and anal
os cos90 0
yzer and parallel
In unpolarised light,
I 0 ........ Equati
vib
on 3
??
? ? ?
? ? ? ? ? ?
? ? ?
??
? ? ?
??
?
??
??
?
? ?
2
av
2
0
2
2
0
rations are probable in all the
direction in a plane perpendicular to the direction of propa

cos
gation
cos
1 cos2

2
.
can have any value from 0 and 2 .
1
d
2
1
2

d
?
?
?
? ? ?
??
??
?? ??
??
?
?
?
?
?
?
? ?
2
0
2
o
o
o
sin2
0
2

1
22
1
2
Using the law of malu

I I cos
s
1
2
I
I
2
I
?
?? ?
?
??
??
??
??
? ? ?
?
??
?
?

Graph:

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

7.
(a) X-rays: Used as a diagnostic tool in medicine and as a treatment for certain
forms of cancer.

8. Consider a charge q moving with velocity v in the presence of electric and
magnetic fields. The force on an electric charge q due to both of them is
? ? ? ?
? ?
? ?
? ?
electric magnetic
where
v velocity of the charge
r location of the charge at a given time
F q E r v B r
F F F ........ Equation 1
=
t
E r Electric field
B r Magnetic field
?? ? ? ?
??
? ? ?
?
?
?

Let us consider a simple case in which electric and magnetic fields are
perpendicular to each other and also perpendicular to the velocity of the
particle.

? ?
E
B
F qE
qEj.F
q v B
ˆ
q vi Bk
qBj
?
?
??
??
??

? ?
F q E vB j ? ? ?
Thus, electric and magnetic forces are in opposite directions.
Suppose we adjust the values of E and B such that magnitudes of the two forces
are equal, then the total force on the charge is zero and the charge will move in
the fields undeflected. This happens when
Page 5

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

CBSE
Class XII Physics – Set 1
Board Paper – All India – 2017 Solution

SECTION A

1. Nichrome wire is heated more
? ?
22
nichrome copper
nichrome copper
Heat dissipate in a wire is given by
H I Rt I t
A
H I, and A remains same
But
HH
?
??
? ? ?
? ? ?
??

2. Yes. As an electromagnetic wave is a combination of electric and magnetic
fields, it carries both energy and momentum. It is given by
hC
E
p mC
?
?
?

where
c = Speed of EM wave in vacuum
? = Wavelength of EM wave

3. If the incident violet light is replaced with red light, then the angle of minimum
deviation of a glass prism decreases.

4. Photoelectric effect shows the quantum nature of electromagnetic radiation.

5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate
B, i.e. polarity of Plate A will be positive with respect to Plate B.

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

SECTION B

6.

Intensity distribution graph for single slit diffraction

Difference between interference pattern and diffraction pattern

Interference Diffraction
It is due to the superposition of two
waves coming from two coherent
sources.
It is due to the superposition of
secondary wavelets originating from
different parts of the same wavefront.
Width of the interference bands is
equal.
Width of diffraction bands is not the
same.

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

OR

According to law of Malus, when a beam of completely plane polarised light is
incident on an analyser ?, resultant intensity of light (I) transmitted from the
analyser varies directly as the square of cosine of angle between the plane of the
analyser and polariser.
? ?
? ?
? ?
? ?
2
2
o
o
I cos
I I cos ........ Equation 1
When 0 or 180
cos 1
I I ........ Equation 2
When 90
c
polarizer and anal
os cos90 0
yzer and parallel
In unpolarised light,
I 0 ........ Equati
vib
on 3
??
? ? ?
? ? ? ? ? ?
? ? ?
??
? ? ?
??
?
??
??
?
? ?
2
av
2
0
2
2
0
rations are probable in all the
direction in a plane perpendicular to the direction of propa

cos
gation
cos
1 cos2

2
.
can have any value from 0 and 2 .
1
d
2
1
2

d
?
?
?
? ? ?
??
??
?? ??
??
?
?
?
?
?
?
? ?
2
0
2
o
o
o
sin2
0
2

1
22
1
2
Using the law of malu

I I cos
s
1
2
I
I
2
I
?
?? ?
?
??
??
??
??
? ? ?
?
??
?
?

Graph:

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

7.
(a) X-rays: Used as a diagnostic tool in medicine and as a treatment for certain
forms of cancer.

8. Consider a charge q moving with velocity v in the presence of electric and
magnetic fields. The force on an electric charge q due to both of them is
? ? ? ?
? ?
? ?
? ?
electric magnetic
where
v velocity of the charge
r location of the charge at a given time
F q E r v B r
F F F ........ Equation 1
=
t
E r Electric field
B r Magnetic field
?? ? ? ?
??
? ? ?
?
?
?

Let us consider a simple case in which electric and magnetic fields are
perpendicular to each other and also perpendicular to the velocity of the
particle.

? ?
E
B
F qE
qEj.F
q v B
ˆ
q vi Bk
qBj
?
?
??
??
??

? ?
F q E vB j ? ? ?
Thus, electric and magnetic forces are in opposite directions.
Suppose we adjust the values of E and B such that magnitudes of the two forces
are equal, then the total force on the charge is zero and the charge will move in
the fields undeflected. This happens when

CBSE XII  | PHYSICS
Board Paper – All India – Set 1 – Solution 2017

qE = qvB
or
E
or v
B
?
This condition can be used to select charged particles of a particular velocity out
of a beam containing charges moving with different speeds (irrespective of their
charge and mass). The crossed E and B fields therefore serve as a velocity
selector.

9. It is given that the energy of the electron beam used to bombard gaseous
hydrogen at room temperature is 12.5 eV.
Also, the energy of the gaseous hydrogen in its ground state at room
temperature is -13.6 eV.
When gaseous hydrogen is bombarded with an electron beam, the energy of the
gaseous hydrogen becomes -13.6 + 12.5 eV = -1.1 eV.
Orbital energy related to orbit level (n) is
? ?
? ?
2
2
13.6
E eV
n
For n 3,
13.6 13.6
E eV eV 1.5 eV
9
3
?
?
?
??
? ? ? ? ?

This energy is approximately equal to the energy of gaseous hydrogen.
This implies that the electron has jumped from n = 1 to n = 3 level.
During its de-excitation, electrons can jump from n = 3 to n = 1 directly, which
forms a line of the Lyman series of the hydrogen spectrum.
Relation for wave number for the Lyman series is
? ?
? ?
22
22
1
7
1
7
1
7
7
1
1
1 1 1
R
1n
For first member n 3
1 1 1 1 1
RR
19 1
3
1 9 1
1.097 10 .........
9
where Rydberg constant R 1.
18
1.097 10
9
1.025 10
097 10
m
m
?
?
??
??
??
??
?
??
?
??
??
??
? ? ? ? ?
??
? ??
??
??
? ??
? ? ?
??
?
??
? ? ? ?
?
? ? ? ?

```
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## Physics Class 12

204 videos|288 docs|125 tests

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