# Physics Class 12th Sample Paper Sa1

Topics: Magnetic field, Maxwell's equations, Electromagnetism Pages: 10 (1337 words) Published: August 26, 2013
NCS/SA-1st/11-12/XII/Physics/70

Total Pages 4

FIRST SUMMATIVE ASSESSMENT : 2011-12
Subject : PHYSICS Time : 3 hrs.
General Instructions:
(i) (ii) (iii) All questions are compulsory. There are 30 questions in total. Questions 1 to 8 carry 1 mark each, 9 to 18 carry 2 marks each, 18 to 27 carry 3 marks and 28 to 30 carry 5 marks each. Use of calculator is not permitted.

Class : XIIth

M.M. : 70

1. 2. 3.

What does q1 + q2 = 0 signify in electrostatics ?

1

In Bohr's model of hydrogen atom, the electron moves around the nucleus in a circular orbit of radius 5x10–11 m. Its time period is 1.5x10–16 second. Find current associated with the electron motion. 1

E I B C

A

4. 5.

Two heater wires of equal lengths are first connected in series and then in parallel. Find ratio of heat produced in two cases. 1

tu

In the circuit shown in fig. the resistances P and R are unequal. If the reading of the galvanometer remains the same with switch S open or closed, then what is the value of current through galvanometer ? 1

di es
IP IR P

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V
B Q
HS

w

A

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D
C G D

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R

6. 7. 8. 9.

How will the magnetic field intensity at the centre of a circular coil carrying current change, if the current through the coil is doubled and the radius of the coil is halved ? 1 Define eddy current. What is the ratio of speed of gamma rays and radiowaves in vacuum ? Prove that energy stored in a parallel plate capacitor is 1/2 CV2. 1 1 2

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Form the graph between current (I) and voltage (V) as shown in the figure, identify the portion corresponding to negative resistance. 1

NCS/SA-1st/11-12/XII/Physics/70

Page 2

10.

S1 and S2 are two parallel concentric spheres enclosing charges Q and 2Q respectively as shown in fig. 2Q 2 Q1 S1 S2

(a) (b) 11. 12.

What is the ratio of the electric flux through S1 and S2 ? How will the electric flux through the sphere S1 change, if a medium of dielectric constant 5 is introduced in the space inside S1 is place of air ? 1+1=2 1+2=2

Give any two limitation of Ohm's Law.

A and B are two points on a circular ring made of uniform wire of resistance R. If the part AB of the ring subtends an angle θ at the centre C of the ring as shown in fig. Prove that the effective resistance between A and B is 2 (2 π – θ ) θ Reff = R 4π2 C r A

.c

θ

13. 14. 15.

Derive microscopic form of Ohm's law.

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r B

2 2

Define the terms magnetic dip and magnetic declination.

17.

18.

Arrange the given E.M. radiations in the descending order fo their frequencies : Infra-red, X-rays, Ultra-violet and gamma rays OR Identify the part of EM spectrum, which is (i) Suitable for radar system used in aircraft navigation. (ii) Adjacent to the low frequency end of the EM spectrum. (iii) Produced in nuclear reaction. (iv) Produced by bombarding a metal target by high speed electrons. 2

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The magnetic flux through a coil perpendicular to its plane is varying according to the relation φ = (4t3 + 5t2 + 8t + 5 ) weber Calculate the induced current through the coil at t = 2 second, if the resistance of the coil.

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16.

Show that Lenz's law is in accordance with law of conservation of energy.

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The two resistors 400 Ω and 800 Ω are connected in series with 6 volt battery. It is desired to measure the current in the circuit. An ammeter of 10 Ω resistance is used for this purpose. What will be the reading in the ammeter ? Similarly, if a voltmeter of 10,000 Ω resistance is used to measure the potential difference across the 400 Ω resistor what will be the reading in voltmeter ? 2 2

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2

½+½+½+½=2

19.

Define electric dipole moment. Calculate electric field intensity at a point on the equitorial line of a dipole. 3...

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