(a)[1]
A light-dependent resistor (LDR) has a resistance of about $500\ \Omega$ in daylight. Give an approximate resistance for the LDR in darkness.
(b(i))[1]
On Fig. 9.1, show the polarity of point $P$ so that the red LED is lit.
(b(ii))[3]
The LDR is in daylight and its resistance is $500\ \Omega$. State and explain which diode, red or green, will be lit.
(b(iii))[2]
The light intensity falls and the LDR is in darkness. State and explain the effect of this change in intensity on the LEDs.