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Question
If the current in the circuit for heating the filament is increased, the cutoff wavelength
Options
will increase
will decrease
will remain unchanged
will change
Solution
will remain unchanged
Cut off wavelength is given by `lambda_min = (hc)/(eV)`,
where h = Planck's constant
c = speed of light
e = charge on an electron
V = potential difference applied to the tube
Clearly, the cutoff wavelength does not depend on the current in the circuit and temperature of the filament.
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