#### First Mid Term Model Questions

12th Standard EM

Reg.No. :
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Physics

Time : 01:00:00 Hrs
Total Marks : 50
5 x 1 = 5
1. Four Gaussian surfaces are given below with charges inside each Gaussian surface. Rank the electric fl ux through each Gaussian surface in increasing order.

(a)

D < C < B < A

(b)

A < B = C < D

(c)

C < A = B < D

(d)

D > C > B > A

2. The value of constant 'K' in coulomb law is

(a)

0.9 x 109 Nm2 C2

(b)

9 x 10-9 Nm2C2

(c)

9 x 109 Nm-2 C-2

(d)

9 x 109 Nm2 C-2

3. For a large charge accumulation, the end of the conductor should have larger curvature that is_________.

(a)

bigger radius

(b)

Smaller radius

(c)

maximum radius

(d)

less bent

4. A carbon resistor of (47 ± 4.7 ) k Ω to be marked with rings of diff erent colours for its identifi cation. Th e colour code sequence will be

(a)

Yellow – Green – Violet – Gold

(b)

Yellow – Violet – Orange – Silver

(c)

Violet – Yellow – Orange – Silver

(d)

Green – Orange – Violet - Gold

5. Th ree wires of equal lengths are bent in the form of loops. One of the loops is circle, another is a semi-circle and the third one is a square. Th ey are placed in a uniform magnetic fi eld and same electric current is passed through them. Which of the following loop confi guration will experience greater torque ?

(a)

circle

(b)

semi-circle

(c)

square

(d)

all of them

6. 5 x 1 = 5
7. Electrostatic force

8. (1)

Applied for circular coil carrying current

9. Dielectric strength

10. (2)

Nichrome

11. Electric Heaters

12. (3)

Newton's III law

13. Right hand thumb rule

14. (4)

To find the polarity of the solenoid

15. End rule

16. (5)

Maximum electric field

5 x 2 = 10
17. What is mean by ‘Electric field lines’?

18. What are Polar molecules.

19. What do you mean by internal resistance of a cell?

20. What is conductor?

21. What do you mean by end resistance? How can it be rectified?

22. 5 x 3 = 15
23. Two small-sized identical equally charged spheres, each having mass 1 mg are hanging in equilibrium as shown in the figure. The length of each string is 10 cm and the angle θ is 7° with the vertical. Calculate the magnitude of the charge in each sphere.(Take g = 10 ms−2)

24. What happens when and electric dipole is held in a non-uniform electric field?

25. When two resistances connected in series and parallel their equivalent resistances are 15 Ω and $\frac{56}{15}$Ω respectively. Find the individual resistances.

26. How will the magnetic field intensity at the contre of a circular coil carrying current change if the current through the coil is doubled and the radius of the coil is halved?

27. A rectangular current carrying loop placed 2cm away from a long, street, current - carrying conductors. What is the direction and magnitude of the net force acting on the loop.

28. 3 x 5 = 15
29. Consider a point charge +q placed at the origin and another point charge -2q placed at a distance of 9 m from the charge +q. Determine the point between the two charges at which electric potential is zero.

30. Use Kirchhoff's laws (rules) to determine the potential difference between points A and D when no current flows in the arm BE of the electric network shown in the figure. below

31. A rectangular coil of area 2 x 10-4 m2 and 40 turns is pivoted about one of its vertical sides. The coil is in a radial horizontal field of 60G. What is the torsional constant of the hair springs connected to the coil if a current of 4.0 mA produces an angular deflection of 16°?