Paper 1 Semiconductors and Diodes Answers

Q	Answer	Reason
1	A	Semiconductors lie between conductors and insulators.
2	B	Thermal energy creates more mobile carriers.
3	B	NTC means negative temperature coefficient.
4	A	More light creates more carriers in an LDR.
5	A	Forward bias allows conduction after threshold region.
6	B	Diode graph is asymmetric and non-ohmic.
7	A	Ideal reverse current is negligible.
8	A	Rectified output is one direction but varying.
9	A	One diode passes one half-cycle.
10	A	The measured component matters.
11	A	Potential divider formula for lower output.
12	A	Lower resistance gets smaller share of supply p.d.
13	A	LDR resistance falls in brighter light.
14	A	Non-linear I-V means non-constant resistance.
15	A	Typical school model.
16	A	Smoothing capacitor is across load.
17	B	Without smoothing, output varies with time.
18	A	Conventional forward-bias condition.
19	A	This controllability is the useful property.
20	A	Reversing the diode changes it from forward bias to reverse bias, for which the current is negligible in the simple model.