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#### Current Electricity One Mark Questions

12th Standard EM

Reg.No. :
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Physics

Time : 00:30:00 Hrs
Total Marks : 20
15 x 1 = 15
1. A toaster operating at 240 V has a resistance of 120 Ω. Th e power is

(a)

400 W

(b)

2 W

(c)

480 W

(d)

240 W

2. 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

3. In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60W bulb for use in India is R, the resistance of a 60W bulb for use in USA will be

(a)

R

(b)

2R

(c)

$\frac{R}{4}$

(d)

$\frac{R}{2}$

4. In Joule’s heating law, when I and t are constant, if the H is taken along the y axis and I2 along the x axis, the graph is

(a)

straight line

(b)

parabola

(c)

circle

(d)

ellipse

5. Which of the following has negative temperature coefficient of resistance?

(a)

copper

(b)

tungsten

(c)

carbon

(d)

silver

6. The temperature co-efficient of resistance for alloys is

(a)

low

(b)

very low

(c)

high

(d)

very high

7. An electron gun in a TV shoots out a beam of electrons. The obeam current is lOll A. The charge that strikes the screen in I minute is

(a)

$+600\mu C$

(b)

$-600\mu C$

(c)

$+10\mu C$

(d)

$-10\mu C$

8. The emf of a battery is 3 volts and internal resistance 0.125 $\Omega$ . The difference of potential
at the terminal of battery when connected across an external resistance of 1 $\Omega$ is

(a)

1.67 V

(b)

0.67 V

(c)

2.67 V

(d)

3.67 V

9. An unknown resistance is connected in parallel with a 15$\Omega$ resistance and a 12V battery. What is the value of the unknown resistance if the current in the circuit is 2A?

(a)

$10\Omega$

(b)

$20\Omega$

(c)

$30\Omega$

(d)

$40\Omega$

10. Conductor which obey ohm's law are called.

(a)

dielectrics

(b)

superconductors

(c)

ohmic conductors

(d)

semiconductors

11. An ideal cell is connected to a capacitor through a voltmeter. The reading V of the voltmeter is plotted against time. Which of the following best represents the resulting curve?

(a)

(b)

(c)

(d)

12. Two identical resistors are connected in parallel then connected in series. The effective resistance are in the ratio

(a)

1:2

(b)

2:1

(c)

1:4

(d)

4:1

13. The resistivity of a wire depends on

(a)

length

(b)

material

(c)

area of cross section

(d)

all the above

14. Generally the instantaneous current is represented by__________

(a)

i

(b)

I

(c)

dI

(d)

di

15. When three resistors are connected in series then the value of the effective resistance is

(a)

less than the individual resistance

(b)

greater than the individual resistance

(c)

greater than or equal to individual resistance

(d)

less than or equal to individual resistance

16. 5 x 1 = 5
17. Electrical Lamp

18. (1)

ohm

19. Current

20. (2)

Tungsten

21. Resistance

22. (3)

watt

23. Power

24. (4)

ampere

25. Energy

26. (5)

joule