Planck's Constant

Pick an option to see whether it holds. If one of them stops you, the theory page is two steps back.

1. 01

   Planck's constant relates energy of a photon to its:

   • a) Mass
   • b) Frequency
   • c) Amplitude
   • d) Electric charge
2. 02

   The 'knee voltage' of an LED is defined as the voltage at which:

   • a) The LED burns out
   • b) The LED starts to glow
   • c) The LED reaches maximum brightness
   • d) The current becomes zero
3. 03

   The formula used to calculate Planck's constant in this experiment is:

   • a) h = eλV / c
   • b) h = mc²
   • c) h = eV / c
   • d) h = cλ / V
4. 04

   In the formula h = eλV / c, 'V' represents:

   • a) Velocity of light
   • b) Knee voltage of the LED
   • c) Volume of the circuit
   • d) Voltage of the battery
5. 05

   Which component is used in the circuit to vary the voltage across the LED?

   • a) Capacitor
   • b) Rheostat
   • c) Inductor
   • d) Transformer
6. 06

   As the wavelength of an LED decreases, its knee voltage:

   • a) Decreases
   • b) Increases
   • c) Remains the same
   • d) Becomes zero
7. 07

   Among Red, Yellow and Green LEDs, which one has the highest knee voltage?

   • a) Red
   • b) Yellow
   • c) Green
   • d) All have the same knee voltage
8. 08

   The SI unit of Planck's constant is:

   • a) Joule
   • b) Joule-second
   • c) Watt
   • d) Joule per second
9. 09

   The accepted standard value of Planck's constant is approximately:

   • a) 6.626 × 10⁻³⁴ J·s
   • b) 3.0 × 10⁸ J·s
   • c) 1.6 × 10⁻¹⁹ J·s
   • d) 9.1 × 10⁻³¹ J·s
10. 10

    In the experiment, 'e' in the formula h = eλV / c represents:

    • a) Efficiency of the LED
    • b) Charge of an electron
    • c) Energy of the photon
    • d) Emissivity constant