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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
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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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