Physics A-Level
Intensity
What Intensity means in Physics A-Level, as defined for AQA, OCR.
Definitions of Intensity
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Reference: AQA
Increasing this increases the number of photons per second, so more electrons are released, but it does not change each photon's energy.
The energy per unit area per unit time; for monochromatic light it is proportional to the number of photons incident per second.
Relates to the number of quanta arriving per second, while frequency determines the energy of each quantum.
The power transmitted per unit area perpendicular to the direction of energy transfer, given by I = P/A.
The power transferred per unit area perpendicular to the direction of energy flow, measured in W m⁻².
Topics that use Intensity
- Sensitivity and frequency response (A-level only) (AQA A-Level)
- The discovery of photoelectricity (A-level only) (AQA A-Level)
- The photoelectric effect (AQA A-Level)
- The photoelectric effect (OCR A-Level)
- Wave motion (OCR A-Level)
Related terms
- Threshold frequency
- Maximum kinetic energy
- Photon
- Work function
- Amplitude
- Compressions and rarefactions
- Conservation of energy in photon absorption
- Diffraction and gap-to-wavelength ratio
Using Intensity in the exam
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