8[1]. electricity asg

7/28/2019 8[1]. Electricity Asg.

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SCIENCE ASSIGNMENT X STEPS A TCY Program _________________________________________________________________________________

STEPS____________________________________________________________G e t f r e e n o t e s f o r C l a s s X a n d I X o n

w w w . t c y o n l i n e . c o m

1

ASSIGNMENT ON ELECTRICITY

TYPE A

ELECTRIC CURRENT AND CIRCUIT

1. How many types of charges are there? What types of charges attract and repel each other?

2. What is the SI unit of charge?

3. Define one Coulomb of charge.

4. Name the device used to measure electric current.

5. What is the difference between conventional and electronic current?

6. What is the fundamental unit of charge?

7. What is the smallest value of charge? Is the charge of 23 e on a body possible? If not, explain the reason.

8. What is the source of electric current?

9. Write the mathematical expression between current and charge. Also define one ampere.

10. Fill in the blank

1 e =_______C

11. The charge on a body always exists as a ______ of the charge of an electron.

12. Conventional current always flows from ______ terminal to ______ terminal of a cell.

13. What is an electric circuit?

14. What do you mean by quantization of charge?

15. A wire is carrying a current of 30 mA. What is number of electrons flowing through wire in one minute?

16. An electron is moving in a circular path of radius 100 m with a speed of 3.7 107 ms1. What will be

the current flowing in the circular path?

17. If all electrons are pulled out from 10 g of copper, what will be total charge constituted?

18. 7.8 1010 electrons and 9.1 1011 protons are flowing per second in opposite direction. What will be

the amount and direction of the current?

19. 8 C of net charge flows across a cross section of a current carrying wire in 5 s. What will be the magnitude

of the current through the wire?

20. 2 A of current passes through a wire in 0.5 s. Calculate the amount of charge flowing through the wire.

21. What is an electric circuit? What are the main components of an electric circuit?

22. An electron beam in a beam tube carries a current of 120 A.

(a) What charge will be delivered to the screen of tube every second?

(b) How many electrons will hit the screen each second?


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TYPE B

ELECTRIC POTENTIAL AND POTENTIAL DIFFERENCE

1. Define electrostatic potential at a point. What is its SI unit?

2. Define potential difference between two points on a conductor. What is need of applying potential

difference across a conductor?

3. Define one volt.

4. Write the mathematical form for electric potential.

5. Name the device used to measure electric potential.

6. A charge free to move will always move from a ______ potential to a ______ potential

7. If the potential at a point A is 6 V and a charged body of 3 C is kept at that place, what does it

mean?

8. Which of the following statements are true?

(a) Potential is a vector quantity.

(b) If both the ends of a conductor are at the same potential, there will be a movement of free

electrons from one end to the other end of the conductor.

(c) Charged particles move from higher potential to the lower potential.

9. What should we do to maintain a continuous flow of electrons from one end to the other end of a

conductor?

10. In metals, conduction happens through the ______.

11. The work done by an agency to carry a 5 C charge from infinity to a point in the electrostatic field is

30 J. Calculate the potential at that point.

12. The electrostatic potential energy of a charge of 10 C at a point in the electrostatic field is 50 J. Calculate

the potential at that point.

13. Calculate the work done in moving a charge of 3 C through a potential difference of 10 V.

14. 24 J of energy is given to a charge while passing through a region whose potential difference is 12 V.

Calculate the magnitude of the charge.

15. 45 mA of current flows through a circuit for 10 minutes. If the potential difference within the circuit is

10 V, calculate the work done in moving the charge.

16. 60 J of work is done in moving a charge through an electric circuit having a 10 V battery. If 5 A of current

flows through the circuit, calculate the duration for which current will flow?


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TYPE C

OHMS LAW AND RESISTORS IN SERIES AND IN PARALLEL

1. How will you define resistance? What is its SI unit?

2. Define Ohms law.

3. What is the function of resistors in a circuit?

4. What is the role of connecting wires within an electric circuit?

5. Match the following:

Physical quantity Units

(A) Charge (i) A

(B) Current (ii) V

(C) Resistance (iii) C

(D) Potential (iv)

6. How much current will be drawn by a load from a source of potential difference 50 V, if the load

resistance is 300?

7. 15 mA current flows through a circuit when the potential difference in the circuit is 3 V. Calculate the

resistance in the circuit.

8. In an electric circuit, a current of 0.3 A flows through a load with resistance 500 ohms. Find the potential

difference in the circuit.

9. To obtain maximum resistance by joining the given resistors, they should be grouped in ______

combination.

10. You are given three equal resistors. How many groups of resistances can be obtained by joining them in

series and parallel combination?

11. Two unequal resistors are connected in parallel across a battery. Which of the following statements is

true?

(i) Same current is set up in both resistors.

(ii) Current through smaller resistor is more.

(iii) Current through larger resistor is more.

(iv) Any of these can be true depending upon the potential difference of battery.

12. A wire of certain length is cut into three equal pieces. Two segments are connected in parallel while third

segment is in series to two parallel wires. If resistance of initial wire is R what will be resistance of final

arrangement?

13. A wire of resistance R and length l is bent into circle shown in figure. Find resistance between A and B.


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14. A boy is having two resistors of different values. He measures their resistances using multimeter by

arranging resistors is series, parallel and individually. The values are 3 , 4 , 12 and 16

respectively. Find the value of the two resistances.

15. Find current in the circuit given below

16. Find resistance between points A and F in the given circuit.

17. One meter long copper wire of thickness 0.5 mm is coiled. What is current through coil if potential

difference of 20 V is applied? (Resistivity of copper is 1.7 108m)

18. Find potential drop across 2 resistance.

A

B

60

4

10 2 5

5

10

10

10 E D

CB

5

A

F

10 V

8

4

2

()

( )

1

4

2 3

5

10 V


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19. A copper wire carrying 5 A current is stretched and its radius becomes half. What will be the change in

current?

20. There are n identical resistors. First the resistors are connected parallel, then in series. Find the ratio of

the total resistances in each combination.

21. Aluminium ball of radius 0.5 cm is drawn into a wire of thickness 0.5 mm. What will be the resistance of

wire? (Resistivity of aluminum is 2.82 108m).

22. Resistance of a metallic wire of length 1 m is 30 and the diameter of the wire is .1 mm. Calculate the

resistivity of the metallic wire.

23. How does the resistance of a metallic wire get affected if its area of cross section becomes half, without

changing the original length?

24. A wire A has uniform diameter and length and another wire B of the same material has twice the

diameter of A and four times the length of A. Find the ratio of the resistances of wires A and B.

25. The resistance of a 10 cm long wire is 50 ohm. The wire is stretched to a uniform wire of 40 cm length.

Calculate the new resistance in ohm.

26. For the given circuit, find the value of A1, A2, A3, V1 , V2.

27. What are the factors on which the resistivity of a conductor depends?

28. The smallest value of resistance that can be obtained by combining n resistors is _____.

29. Four wires each of resistance R, of same length, diameter and material are joined together to form a

square. Calculate the total resistance across the opposite corners.30. Which of the following statements are true?

(i) In parallel combination of resistors, voltage across each resistor is different.

(ii) In series combination of resistors, current across each resistor is same.

31. Current in a circuit is2

1A. A lamp of resistance R is connected in series with two resistors of 2 and

A2

A1

A3

V1

10 V

100

V2

200


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3 and a voltage source 3 V. Calculate the value of R and the potential drop across the lamp.

32. Derive an expression for equivalent resistance, when three resistors are connected in parallel

combination.

33. If a copper wire is stretched to make it 2 percent longer, what will be the percentage change in its

resistance?

34. A number of light bulbs are connected to a single power supply. In which combination (series or parallel),

they will give more intensity of illumination and why?

35. A 30 W bulb and 60 W bulb are joined in series and connected to main supply. Which bulb will glow

brighter and why? When the series combination is replaced by parallel combination, which bulb will glow

brighter?

36. A 60 W electric bulb in series with a geyser is connected across the main supply. If 60 W bulb is replaced

by 100 W bulb, how will the geysers output will be effected?

37. You have been given three resistances 3, 4, 5. How will you combine them to give equivalent

resistance of

(i)9

47 (ii)

12

35

38. Refer to the figure below and calculate the effective resistance of the network.

39. Find the current in the circuit given below.

R

R

R

R

R

R

R

R

R

10 V

10 4 8 8

3 2

4


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TYPE D

HEATING EFFECT OF ELECTRIC CURRENT AND ELECTRIC POWER

1. One meter wire is obtained by connecting half of the copper and half of the aluminum wire of same

thickness of 0.5 mm. Potential difference of 100 V is applied to the wire. Which segment will heat up

fast? (Resistivity of copper is 1.72 108m and that of aluminum is 2.83 108m)

2. Ten 10 identical resistances are connected in series and then in parallel. 220 V is applied in each case.

Find ratio of power generated in series to parallel combination.

3. Explain heating effect of current.

4. What is an electric power? What is its unit?

5. Two bulbs B1 and B2 of power ratings 40 W/220 V and 60W/220 V are connected parallel to each other.

What is ratio of current through them?

6. The power rating of an electric press is 600 W/ 220 V. Press is operating at 220 V. Sita irons cloths for 2

hours daily. If the initial reading of electricity meter is 0943.0 on August 1, what will be the reading of

the electricity meter till the end of August?

7. Which quantity is measured in kilowatthour?

8. An electric lamp is marked at 100 W/ 220 V. Find the resistance of the filament of the lamp.

9. Define commercial unit of energy.

10. An electric lamp is operating at 100 V. Calculate the power consumed by it if it is rated at 200 V/100 W.

11. Two electric lamps of power 100 W and 200 W are connected in series and voltage source of 220 V is

applied across them. What will be the power consumed by them?

12. A 220 V/ 600 W electric kettle and four 60 W bulbs are connected in parallel. This combination is

connected to 220 V supply. What will be the total current?

13. An electric bulb is marked at 100 W/220 V is connected to a power supply of 100 V. What is the heat

and light energy produced by the bulb in 10 minutes?

14. An electric press rated at 220 V and 1000 W is connected to supply voltage 220 V. What is the resistance

of the press? What is the cost of operating the press for 2 hours daily for 15 days, if the price of electricity

is 1.50 rupees per unit?

15. 50 J of heat is produced each second in 10 load resistance. Find the potential difference across the load

resistance.

16. Find the expression for the rate at which heat is produced in a resistor R connected to a source of voltage

V. Write the units in which this rate is measured.

17. Define electric power .What is its unit?

18. Prove that 1 kWh = 3.6 106 J

19. Find the ratio of power dissipated in the resistors R1 and R2.

5 V

R1 =2

R2 =4


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ANSWER KEY

TYPE A

10. 1.6 1019 11. multiple 12. +ve,ve 15. 1.12 1019

16. 9.4 109 A 17. 4.4 105 C 18. 1.6 107 A current along the direction of protons.

19. 1.6 A 20 1 C 22. 1.2 104 C, 7.5 1014

TYPE B

6. higher, lower 8.(c) 10. free electrons 11. 6 V

12. 5 V 13. 30 J 14. 2 C 15. 270 J

16. 1.2 s

TYPE C

5. (A) (iii), (B) (i), (C) (iv), (D) (ii) 6. 0.2 A 7. 200 A

8. 150 V 9. series 10. 4 11. (ii)

12.2

R13.

36

5R 14. 4 , 12 15. 6.7 A

16.9

104 17. 231 A 18.

14

60V 19. It decreases four times

20.2n

121. 0.39 22. 2.36 107m

23. It increases two times 24. 1:1 25. 3000

26. A1=20

3A, A2=

10

1A, A3=

20

1A, V1=10 V, V2=10 V 28. parallel combination

29. R 30. (ii) 31. 1,2

1V 33. 4 percent

37. (i) 3 resistor in parallel combination of 4 and 5 resistor

(ii) 5 resistor in parallel with series combination of 3 and 4 resistors

38. 3 R 39.78

275A 40.

6

19 41. 5 appx

42. 3 V 43. (i)27 (ii)

710A (iii)

720V

TYPE D

2. 1:100 5. 2:3 6. 0980.2 8. 484

10. 25 W 11. 66.7 W 12. 3 A 13. 15 kJ

14. 48.4 , 45 rupees 15. 22.3 V 19. 2 : 1

8[1]. electricity asg

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