As Electricity- quick circuit question. Watch
Just been revising electricity and got stuck on the last part of this question. The 1st part of the working shows that the pd across the LDR is the same as that across the resistor R (0.75) and I'm not sure why. Please could someone explain this.
For a particular light intensity the resistance of the LDR is 50 kΩThe resistance of R is 5.0 kΩand the variable resistor is set to a value of 35 kΩ
cos there's your clue
the resistance of the fixed resistor R = 5.0k (from part a)
LDR resistance at the intensity of interest = 5.0k (from part c)
both the fixed resistor and the LDR carry the same current because they are in series
...so the PD across both must be equal