# Coulombs law Questions

1. Jun 20, 2009

### ydna7

Q1. A charge of 4000μC passes each point in a wire in 50s
Calculate: a) the charge in coulombs
b) The current in the wire
c) The number of electrons per second passing each point in the wire (Electron charge = 1.6 * 10^-19 C)
Q.2 A 240V kettle transfers 6.9*10^5 joules of energy in 5 minutes. What is the current in the kettle?
Q.3 When hot an electric bar fire has resistance of 50ohms. When connected to the mains supply (240V) what is its power?

Really struggling with this..

Last edited: Jun 20, 2009
2. Jun 20, 2009

### bobaustin

I'm sure you can find these in your book:
current=charge/time
charge=(#electrons)(electron charge)
power=(current)(voltage)
power=work/time

3. Jun 20, 2009

### ydna7

I have been away alot lately and have fallen behind a bit..
so a) = 4000/50=80 coulombs?
b) (#electorons=?)(4000)=??
c)

4. Jun 21, 2009

### dx

a) doesn't make sense. Charge where? Is this part of a bigger question?

5. Jun 21, 2009

### bobaustin

It looks like (a) is trivial: 1 uC is 10^-6C

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