TS Polycet (Polytechnic) 2020 Previous Question Paper with Answers And Model Papers With Complete Analysis

Section – II
PHYSICS

Q) What is the position of the image if the object is placed beyond the centre of curvature on the principal axis of convex lens?
A) at F
B) at C
C) between C and F
D) at infinity

View Answer

C) between C and F

Q) Two metallic wires ’A’ and ‘B’ are having same cross-sectional areas and same current passes through them. Find ratio of drift velocity of electrons in wire ‘A’ and B’.
[electron density of wire A = 8.0 x 10²⁸m^-3 and
electron density of wire B = 9.0 x 10²⁸m^-3
A) 8/9
B) 9/8
C) 16/27
D) 27/16

View Answer

B) 9/8
Explanation: Ratio of drift velocity of electrons in wire ‘A’ and ‘B’
= $\begin{array}{l}\frac1{Electron\;density\;of\;wire\;A}\\\frac1{Electron\;density\;of\;wire\;B}\end{array}$

= $\begin{array}{l}\frac1{Electron\;density\;of\;wire\;B}\\\frac1{Electron\;density\;of\;wire\;A}\end{array}$

= $\frac{9.0x1028m-3}{8.0x1028m-3}$

= 9/8
[Because of same cross-sectional areas and same current passes]

Q) Three conductors having resistance values 2 ohm, 3 ohm and 4 ohm are connected in parallel. Find equivalent resistance.
A) 20 ohm
B) 9 ohm
C) 13/12 ohm
D) 12/13 ohm

View Answer

D) 12/13 ohm
Explanation: Equivalent resistance
1/R = 1/R₁+1/R₂+1/R₃
1/R = 1/2+1/3+1/4 = $\frac{6+4+3}{12}$

= 3/12
∴ R = 12/13 ohm

Q) What is the lens makers formula?
A) $\frac1f= (\mu+1)\frac1{R1}-\frac1{R2}$
B) $\frac1f= (\mu-1)\frac1{R1}-\frac1{R2}$
C) $\frac1f= (\mu+1)\frac1{R1}+\frac1{R2}$
D) $\frac1f= (\mu-1)\frac1{R1}+\frac1{R2}$

View Answer

B) $\frac1f= (\mu-1)\frac1{R1}-\frac1{R2}$

Q) Which of the following relation is correct regarding potential difference (V)?
A) V = FI/q
B) V= Fq/I
C) V=I/Fq
D) V=q/FI

View Answer

A) V = FI/q

Q) Which of the following materials has high value of specific resistance?
A) Copper
B) Silicon
C) Glass
D) Iron

View Answer

C) Glass

Q) When two ends of a conductor are connected to terminals of battery, what happens inside conductor?
A) Electrons move randomly
B) Electrons come to rest
C) Non-uniform electric field creates
D) Uniform electric field creates

View Answer

D) Uniform electric field creates

Q) What is the focal length of a double concave lens kept in air with two spherical surfaces of radii R₁ = 30 cm, R₁ = 60 cm and refractive index of glass is n = 1.5 ?
A) 40cm
B) -40cm
C) 50cm
D) -50cm

View Answer

B) -40cm
Explanation: 1/f = (n-1) (1/R₁+1/R₂)
= (1.5-1)(1/-30 – 1/60)
= (0.5) (-2-1/60) = 0.5x-3/60 = -0.5/20
∴ f= 20/0.5 = 200/-5 = -40cm

Q) If force acting on current carrying conductor inside a magnetic field is F = $\frac{IlB}{\sqrt2}$ . Find the angle between plane of 72conductor and magnetic field intensity direction.
A) 90°
B) 60°
C) 45°
D) 30°

View Answer

C) 45°
Explanation: F = IlB sinθ =IlB/ √2
∴ sinθ = 1/ √2 = 45°

Q) The graph shows relation between induced emf (∅) and time (t). During which time period there is no change in induced electromotive force?

A) 6 to 12
B) 2 to 6
C) 0 to 6
D) 6 to 8

View Answer

B) 2 to 6

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Section – II PHYSICS

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Section – II
PHYSICS