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## AaronAndyson one year ago http://prntscr.com/8ie2s0

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1. zzr0ck3r

that looks like Chinese to me.

2. AaronAndyson

Okay.I'll type the question.

3. AaronAndyson

Three resistors are connected in parallel.Draw a circuit including a switch and a battery . Derive the equivalent resistance of such a circuit.

4. AaronAndyson

@zzr0ck3r You there?

5. zzr0ck3r

nono I am saying I don't know the subject...

6. zzr0ck3r

lol

7. AaronAndyson

@welshfella @Abhisar

8. Abhisar

Do you know anything about Ohm's law?

9. AaronAndyson

Yep.

10. Abhisar

Good, so lets's start. I'll leave part (a) for you.

11. AaronAndyson

Actually,I got part(b) also.

12. AaronAndyson

Stcuk at part(c)

13. AaronAndyson

Stuck*

14. Abhisar

Ok, current in the circuit can be calculated by using the formula, $$\sf \boxed{\Large I=\frac{Emf}{r+R}}$$

15. Abhisar

r=internal resistance, R=external resistance

16. AaronAndyson

Curent = 0.06A?

17. AaronAndyson

0.096*

18. Abhisar

Yes.

19. AaronAndyson

I've no idea how to go about the rest :(

20. Abhisar

Potential difference across each resistor: You know the current flowing (I) now. use V=IR for each resistor. E.g. across 20 ohms resistor voltage drop will be 0.096*20

21. AaronAndyson

0.96*2?

22. Abhisar

WHat?

23. AaronAndyson

1.92V?

24. AaronAndyson

p.d across 20 ohm resistor is 1.92?

25. Abhisar

YEs.

26. AaronAndyson

and the latter is 0.48?

27. AaronAndyson

i.e across the 5 ohm resistor.

28. Abhisar

Yes

29. AaronAndyson

and across the cell?

30. Abhisar

Ok, let's do the last one first... When the current is flowing, then the potential difference between the terminals of the cell < EMF and that potential drop V is given by, V= (emf of the cell) - Current X internal resistance. V= 2.5 - 0.096 X 1

31. Abhisar

Getting it? This is the solution for last one....

32. AaronAndyson

wait what?

33. AaronAndyson

that should be the p.d across the cell...

34. Abhisar

Nuuu...I explained it wrong earlier....chuck that from ur mind..

35. Abhisar

Is it clear now???

36. AaronAndyson

OK!

37. AaronAndyson

so p.d across the cell is?

38. Abhisar

Recall what we did to find the pd across resistors??? We multiplied their individual resistances with current flowing..Right?

39. AaronAndyson

Yep.

40. Abhisar

Similarly, to find pd across the cell we will multiply the current with resistance of cell i.e. internal resistance...

41. Abhisar

Can you find it for me?/

42. AaronAndyson

You mean 2.5*1?

43. Abhisar

What's the current?

44. AaronAndyson

0.096*2.5 = p.d across the cell?

45. Abhisar

Nuu..Current X Internal resistance....

46. Abhisar

Current = ? Internal resistance = ?

47. AaronAndyson

Ugh...idk...... :'(

48. AaronAndyson

Internal resistance = 1 ohm

49. Abhisar

Internal resistance is given in the question and we calculated the current in 1st part :O

50. AaronAndyson

I know...Zoned out xD

51. AaronAndyson

Current is 0.096A and Internal Resistance is 1 ohm

52. AaronAndyson

Voltage drop = current*internal resitance right?

53. AaronAndyson

resistance*

54. Abhisar

Yes

55. AaronAndyson

so 0.096 is the voltage drop?

56. Abhisar

$$\huge \checkmark$$ Voltage drop across the cell

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