Calculation Crunch
Common Exam Mistakes
Photoelectric effect
Electromagnetism
Waves & Light
100

The equation used to determine the number of electrons passing a point in a circuit.

What is N = Q/e

100

Increasing light intensity increases this in the photoelectric effect.

What is the number of photoelectrons emitted?

100

The quantum of electromagnetic radiation.

 What is a photon?

100

The law stating induced current opposes the change producing it.

 What is Lenz's Law?

100

The relationship between speed, frequency and wavelength.

 What is v=fλ

200

A current of 4.0 A flows for 3.0 s.

What is 12 C?

200

Increasing light intensity increases this quantity.

Students must identify the misconception.

What is NOT the maximum kinetic energy of photoelectrons?

200

The minimum energy required to remove an electron.

 What is the work function?

200

A changing magnetic flux produces this.

What is an EMF?

200

Sound waves are classified as this type of wave.

What is longitudinal?

300

A transformer has 200 primary turns and 50 secondary turns. Input voltage is 240 V.

What is 60 V?

300

During melting, temperature remains constant because added energy increases this.

What is potential energy?

300

The equation connecting photon energy and frequency.

What is the threshold frequency?

300

The right-hand rule is commonly used to determine this.

What is magnetic field direction?

300

Light bends toward the normal when entering a slower medium because its ______ decreases.

What is speed?

400

Light travels from glass (n = 1.50) to air. Calculate the critical angle.

What is 41.8°?

400

A voltmeter should ideally have this resistance.

What is infinite resistance?

400

Explain why increasing intensity cannot produce photoelectrons if frequency is below threshold.

Because individual photons do not possess sufficient energy to overcome the work function.

400

Which particle experiences the greatest magnetic force in a field: stationary proton or moving proton?

What is the moving proton?

400

The phenomenon responsible for bright and dark fringes in Young's double slit experiment.

What is interference?

500

 A proton and electron are separated by 5.3×10−11 m.

What is 8.2×10−8

500

An ammeter should ideally have this resistance.

What is zero resistance?

500

The minimum frequency needed to produce photoelectrons.

What is the threshold frequency?

500

Why does a charged particle move in a circle when entering a magnetic field perpendicular to its velocity?

Because the magnetic force acts as a centripetal force.

500

Explain why total internal reflection can only occur when travelling from higher refractive index to lower refractive index.

Because the refracted angle must reach 90°, which only occurs when light attempts to move into a less optically dense medium.

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