OCR B Physics potential divider help

username1482097

Hi, just doing a past paper and came across this question, could somebody possibly draw the diagram and explain it to me please, Thanks :smile:

http://puu.sh/hvw72/e3de9c6d4f.png

Reply 1

T-the-Dreamer

I think I've done the past paper it's from lol

I can't seem to be bothered to draw the diagram atm (I'm sorry for being so lazy). Your battery, LDR and fixed resistor would be connected in series. Your voltmeter would then be connected in parallel with the fixed resistor.

Why you ask?

The resistance of a LDR goes down with the amount of light on it. So from V=IR, a decreasing resistance means there is a decrease in p.d. in the LDR.

Since the resistors are in series, the p.d. is split in proportion with their resistances - a falling resistance in the LDR would lead to the fixed resistor having a greater share of the voltage.

I'm a bit rusty on this, but that should be it. Hoped it helped :smile:

Reply 2

username1482097