# Homework Help: A2 Physics help

1. Jun 23, 2007

### CathyLou

Hi.

15.15 A capacitor is joined in series with a resistor, a low resistance microammeter, a switch and a 12 V battery.

(a) When the switch is first closed, what is

(i) the p.d. across the capacitor

(ii) the p.d. across the resistor

(iii) the current

(iv) the charge on each of the capacitor plates?

(b) Calculate also the same quantities when the switch has been closed for some time so that steady conditions have been reached.

(c) If the capacitor had continued to charge at its initial rate, how long would it have taken to become fully charged?

15.16 In the previous question, at a certain instant after the switch has been closed the microammeter reads 9.5 μA. Calculate, for this instant

(a) the p.d. across the resistor

(b) the p.d. across the capacitor

(c) the charge on each of the capacitor plates?

Thank you.

Cathy

2. Jun 23, 2007

### malawi_glenn

3. Jun 23, 2007

### CathyLou

For (a) (i) I wrote down 12 V, but I'm not sure if this is correct or how to do the next parts.

4. Jun 23, 2007

### malawi_glenn

how did you perform your calculations? What relationsships are there bewteen resistance, current and voltage ? What is the function of a capacitor? What is the capacitors capacitance?