CBSE Class 12 Applied Physics Question Paper 2020

H$moS> Z§.
Code No. 105
amob Z§.
Roll No.

ZmoQ> NOTE
(I) H¥$n`m Om±M H$a b| {H$ Bg àíZ-nÌ _o§ _w{ÐV (I) Please check that this question
n¥ð> 5 h¢ & paper contains 5 printed pages.

(II) àíZ-nÌ _| Xm{hZo hmW H$s Amoa {XE JE H$moS (II) Code number given on the right
>Zå~a H$mo N>mÌ CÎma-nwpñVH$m Ho$ _wI-n¥ð> na hand side of the question paper
{bI| & should be written on the title page of
the answer-book by the candidate.
(III) H¥$n`m Om±M H$a b| {H$ Bg àíZ-nÌ _| (III) Please check that this question
>4 àíZ h¢ & paper contains 4 questions.
(IV) H¥$n`m àíZ H$m CÎma {bIZm ewê$ H$aZo go (IV) Please write down the Serial Number
nhbo, CÎma-nwpñVH$m _| àíZ H$m H«$_m§H$ of the question in the answer-book
before attempting it.
Adí` {bI| &
(V) Bg àíZ-nÌ H$mo n‹T>Zo Ho$ {bE 15 {_ZQ >H$m (V) 15 minute time has been allotted to
g_` {X`m J`m h¡ & àíZ-nÌ H$m {dVaU read this question paper. The
nydm©• _| 10.15 ~Oo {H$`m OmEJm & question paper will be distributed
10.15 ~Oo go 10.30 ~Oo VH$ N>mÌ Ho$db at 10.15 a.m. From 10.15 a.m. to
10.30 a.m., the students will read the
àíZ-nÌ H$mo n‹T>|Jo Am¡a Bg Ad{Y Ho$ Xm¡amZ question paper only and will not
do CÎma-nwpñVH$m na H$moB© CÎma Zht {bI|Jo & write any answer on the
answer-book during this period.

ì`mdhm[aH$ ^m¡{VH$s (g¡ÕmpÝVH$)
APPLIED PHYSICS (Theory)
{ZYm©[aV g_` : 3 KÊQ>o A{YH$V_ A§H$ : 60
Time allowed : 3 hours Maximum Marks : 60

.105 1 P.T.O.

{ZX}e : g^r àíZm| Ho$ CÎma Xr{OE &
1. (a) {dÚwV²-joÌ H$s Vrd«Vm H$mo n[a^m{fV H$s{OE & BgH$m Eg.AmB©. _mÌH$ {b{IE &
EH$ {~ÝXþ Amdoe Ho$ H$maU CËnÞ {dÚwV²-joÌ H$s Vrd«Vm H$m gyÌ {b{IE & EH$
50 C Ho$ Amdoe go 50 go_r Xÿar na {dÚwV²-joÌ H$s Vrd«Vm H$s JUZm H$s{OE & 5

(b) g§Ym[aÌ Š`m hmoVm h¡ ? EH$ g§Ym[aÌ _| g§{MV D$Om© Ho$ {bE gyÌ ì`wËnÞ H$s{OE & 5
AWdm
VrZ g§Ym[aÌm| H$mo loUr~Õ H«$_ _| bJmZo H$mo Xem©Zo Ho$ {bE EH$ {MÌ ~ZmBE & O~
VrZ g§Ym[aÌm| H$mo loUr~Õ _| Omo‹S>m OmVm h¡, Vmo CZH$s ewÕ Ym[aVm Ho$ {bE gyÌ
{b{IE & 2 F, 3 F d 6 F Ho$ VrZ g§Ym[aÌm| H$mo loUr~Õ H«$_ _| Omo‹S>m J`m
h¡ & ewÕ Ym[aVm kmV H$s{OE & 5

(c) Jm°g à_o` H$mo n[a^m{fV H$s{OE & Bg à_o` H$m à`moJ EH$ ImoIbo Amdo{eV
MmbH$ Ho$ AÝXa {dÚwV²-joÌ H$s Vrd«Vm kmV H$aZo Ho$ {bE H$s{OE & 5

2. (a) Mwå~H$s` joÌ H$mo n[a^m{fV H$s{OE & Mwå~H$s` joÌ H$s Vrd«Vm H$m Eg.AmB©.
_mÌH$ {b{IE & EH$ grYo Ymamdmhr MmbH$ Ho$ H$maU CËnÞ hmoZo dmbr Mwå~H$s`
joÌ H$s Vrd«Vm Ho$ {bE gyÌ {b{IE & MmbH$ H$s gVh na Mwå~H$s` joÌ H$m _mZ
Š`m hmoJm ? 5

(b) Mwå~H$s` joÌ _| J{V_mZ EH$ Amdoe na bJZo dmbm ~b {H$Z-{H$Z H$maUm| go
à^m{dV hmoVm h¡ ? ~b Ho$ {bE gyÌ {b{IE & CZ n[apñW{V`m| H$mo {b{IE O~
Amdoe na (i) A{YH$V_, Am¡a (ii) Ý`yZV_ ~b bJVm h¡ & 5

AWdm
Mwå~H$s` A{^dmh KZËd d Mwå~H$erbVm nXm| H$mo n[a^m{fV H$s{OE & BZH$m
Eg.AmB©. _mÌH$ {b{IE & Cg nXmW© H$m Zm_ {b{IE {OgH$s Mwå~H$erbVm
A{YH$ hmo & 5

(c) EH$ Ymamdmhr d¥ÎmmH$ma Hw$ÊS>br Ho$ Ho$ÝÐ na Mwå~H$s` joÌ H$s Vrd«Vm Ho$ {bE
ì`§OH$ ì`wËnÞ H$s{OE & 5

.105 2

Instructions : Attempt all questions.
1. (a) Define electric field intensity. Give its SI unit. Write the formula
for electric field intensity due to a point charge. Calculate the
electric field intensity at a distance of 50 cm from a charge of
50 C. 5

(b) What is a capacitor ? Derive a formula for the energy stored in a
capacitor. 5
OR

Draw a figure showing the combination of three capacitors in
series. Write the formula for the net capacitance when three
capacitors are connected in series. Three capacitors of 2 F, 3 F
and 6 F are connected in series. Find the net capacitance. 5

(c) Define Gauss theorem. Apply this theorem to find the electric field
intensity inside a hollow charged conductor. 5

2. (a) Define magnetic field. Write the SI unit of magnetic field intensity.
Write the formula for the magnetic field intensity due to a straight
current-carrying conductor. What is the value of the magnetic field
at the surface of the conductor ? 5

(b) What are the factors that affect the force on a charge moving in a
magnetic field ? Write the formula for the force. State the cases
when the charge will experience (i) maximum, and (ii) minimum
force. 5
OR

Define the terms Magnetic flux density and Permeability. Write
their SI units. Write the name of a substance having large
permeability. 5

(c) Derive an expression for the magnetic field intensity at the centre
of a current-carrying circular coil. 5
.105 3 P.T.O.

3. (a) Zm{^H$s` {dIÊS>Z d Zm{^H$s` g§b`Z H$mo n[a^m{fV H$s{OE & BZ_| VrZ AÝVa
{b{IE & 5

(b) ao{S>`mo g_ñWm{ZH$ Š`m hmoVo h¢ ? Xmo ao{S>`mo g_ñWm{ZH$m| Ho$ Zm_ {b{IE d àË`oH$
H$m EH$-EH$ Cn`moJ {b{IE & 5

AWdm
{d{H$aU ˜Vao Š`m hmoVo h¢ ? Xmo {d{H$aU ˜Vam| Ho$ Zm_ {b{IE & {d{H$aU ˜Vam| go
h_ IwX H$mo H¡$go ~Mm gH$Vo h¢ ? 5

(c) Zm{^H$s` [aEoŠQ>a Ho$ {gÕmÝV, aMZm d H$m`©àUmbr H$mo g_PmBE & 5

4. (a) AY©MmbH$ Š`m hmoVo h¢ ? Ge d Si H$s AmpÊdH$ g§aMZm Xr{OE & AY©MmbH$m| H$s
MmbH$Vm Vmn_mZ ~‹T>Zo na {H$g àH$ma à^m{dV hmoVr h¡ ? 5

(b) p-n O§ŠeZ H$m àVrH$-{M• ~ZmBE & AJ«{X{eH$ ~m`g _| p-n O§ŠeZ H$m
{dÚwV²-n[anW ~ZmBE & AJ«{X{eH$ ~m`g _| p-n O§ŠeZ H$s H$m`©àUmbr
g_PmBE & 5

AWdm
{Xï>H$mar Š`m hmoVm h¡ ? nyU©Va§J {Xï>H$mar Ho$ ê$n _| p-n O§ŠeZ H$s H$m`©àUmbr
g_PmBE & 5

(c) n-p-n Q´>m§{µOñQ>a H$m àVrH$-{M• ~ZmBE & C{MV ~m`qgJ H$m à`moJ H$aVo hþE
n-p-n Q´>m§{µOñQ>a H$m {dÚwV²-n[anW ~ZmBE d Q´>m§{µOñQ>a {H«$`m (n-p-n Q´>m§{µOñQ>a H$s)
H$s ì`m»`m H$s{OE & 5

.105 4

3. (a) Define nuclear fission and nuclear fusion. Give three differences
between them. 5

(b) What are radio-isotopes ? Write the name of two radio-iostopes and
write one use of each. 5
OR

What are radiation hazards ? Name two radiation hazards. How
can we protect ourselves from radiation hazards ? 5

(c) Explain the principle, construction and working of a nuclear
reactor. 5

4. (a) What are semiconductors ? Give the atomic structure of Ge and Si.
How is the conductivity of semiconductors affected by rise in
temperature ? 5

(b) Draw the symbol of p-n junction. Draw a circuit diagram of
p-n junction in forward biasing. Explain the working of a p-n
junction in forward biasing. 5
OR

What is a rectifier ? Explain the working of a p-n junction as a
full-wave rectifier. 5

(c) Draw a symbol of an n-p-n transistor. Draw a circuit diagram of
n-p-n transistor with proper biasing and explain transistor action. 5

.105 5 P.T.O.