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JEE Mains · Physics · STD 12 - 11. Dual nature of radiation and matter
A metal surface is illuminated by a radiation of wavelength \(4500 \; \mathring A\). The ejected photo-electron enters a constant magnetic field of \(2 \; mT\) making an angle of \(90^{\circ}\) with the magnetic field. If it starts revolving in a circular path of radius \(2 \; mm\), the work function of the metal is approximately ............. \(eV\)
- A \(1.36\)
- B \(1.69\)
- C \(2.78\)
- D \(2.23\)
Answer & Solution
Correct Answer
(A) \(1.36\)
Step-by-step Solution
Detailed explanation
\(\lambda=4500 \; \mathring A\) \(B =2 \; mT , R =2 \; mm\) \(R =\frac{\sqrt{2 \; Km }}{ qB }\) \(\frac{(q B R)^{2}}{2 \; m}=K\) \(\frac{\left(1.6 \times 10^{-19} \times 2 \times 10^{-3} \times 2 \times 10^{-3}\right)^{2}}{2 \times 9.1 \times 10^{-31}}= K\)…
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