Question

a torch bulb is rated 3v and 600mA.calculate the resisitance if it is lighted for 4hrs.

Answer 1

V=IR i don't know if resistance depends upon time :P

Answer 2

hmmmm

Answer 3

so answer is 5Kohm.

Answer 4

hmm ok

Answer 5

well i am not sure about zero's plz recheck i ddnt used calculator

Answer 6

k anywy thx 4 trying it @theyatin

Answer 7

When a bulb is cold or initially turned on, it resistance is much lower.

Answer 8

cn u show me d steps frm beginning

Answer 9

exactly mr radar. . .
so as the cfl bulbs do it gives its maximum intensity after a while. . .

Answer 10

plzzzzzzz do it frm beginning i am very poor in physics plzzzzzzzzzzzzzzzzzz help me guyzzz

Answer 11

@radar

Answer 12

@ujjwal cn u do it????????

Answer 13

I am not that familiar with the CFI bulb......sorry

Answer 14

dnt luk dt cn u solve ma porb

Answer 15

The time is given in the question just to mislead you. If it had something to do with time, temperature coefficient of resistance would be given. But there is no clue about it. So, the answer is 5 K \(\Omega\).
And if you have never heard the term temperature coefficient of resistance, you don't need it now.

Answer 16

nothing special just equation voltage=current *resistence thats it you have the answer.
V=IR.
bulb luminates depending on its heating element which when cool offers more resistance that this equation after some time when its completly heated it will follow this equation completely.

Answer 17

The CFL bulb would normally work off of a higher voltage. @ujjwal is right, the time is just to let you know that the bulb has been on awhile and has stabilized. You do not need to use the 4 hours in your computation.......Ohms Law is your friend.

Answer 18

exactly thats why i wrote some time rather than few hours. . .
@radar
cfl works on lower voltage gives way more luminosity than a heating element bulb. . .
a 13W cfl is enough to replace 6oWelement bulb

Answer 19

Usually a buld that uses a plasma, has first a higher ignition voltage, then a lower sustaining voltage. No question it is more efficient than a incandescent bulb. I was raised up with wicks in kerosene. lol

Answer 20

@radar Same here. But it doesn't really matter how you were raised.

Answer 21

So true, but it does make you appreciate electricity!

Answer 22

Aye, All thanks to Nikola Tesla, Wizard of electricity....

Answer 23

And radio, which I also appreciate.

Answer 24

My call is WD4AIR

Answer 25

was it true that Nikola would power the whole world for free? That project was incomplete due to JP Morgan..

Answer 26

I don't know, but I have found that there is very little for free. And for what you may think is free, may have a hidden price.

Answer 27

exactly. After all nothing is for free.. But at times we have to pay very less..

Answer 28

True enough, Nice chatting with you. I think the solution was 5,000 Ohms. lol

Answer 29

LOL.

Answer 30

Now after looking at it again the answer is 5 Ohms not 5K Ohms

Answer 31

Let me see if I can get back to @Parvathysubhash, Sir I miscalculated. 3 volts/ 600 ma
is 3V/.6 amp = 5 Ohms.

Answer 32

LOL. yeah, I hadn't even calculated it.

Answer 33

k cn u guyzz do it frm beginning
step by step

Answer 34

Are there any steps? see Radar'd last comment. He has solved it correctly there.

Answer 35

*radar's