Paper 1 - Written Answers

Question 1

Quantum

Wave-Particle Duality

Answer 1

Wave as Particles;
photoelectrons emitted immediately
number of photoelectrons emitted per second dependent on intensity of light
waves only transfer energy over time

Particle as wave:
electrons passed through diffraction grating
expect to see one maxima in centre
shown interference patter -> waves create intereference patterns

Question 2

Quantum

Fluorescent tube

Answer 2

• Mercury atoms collide with each other and electrons in tube
• electrons in mercury absorb energy and become excited
• electrons return to ground state and emit UV photon
• electrons in coating absorb energy and become excited
• coating electrons de-excite and emit visible photon

Question 3

Electricity

Temp. and resistance

Answer 3

• As temp increases, lattice vibrations increase
• increase number of collisions per second with electrons
• increases resistance

Question 4

Electricity

How Diodes Work

Answer 4

• As voltage increases, energy of weakly bound electrons increases
• Above threshold frequency, weakly bound electrons have enough energy to leave structure and carry charge
• Lattice vibrations increase, but insignificant