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Sodium and copper have work functions 2....

Sodium and copper have work functions 2.3 eV and 4.5 eV respectively. Then the ratio of the threshold wavelengths is nearest

A

`1 : 2`

B

`4 : 1`

C

`2 : 1`

D

`1 : 4`

Text Solution

Verified by Experts

The correct Answer is:
C
Work function
`W_(0)=hf_(0)=(hc)/lambda_(0)implies W_(Na)/W_(Cu)=lambda_(Cu)/lambda_(Na)`
`lambda_(Na)/lambda_(Cu)=W_(Cu)/W_(Na)=4.5/2.3 ~~2`
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