The work function of metal is 4.2 e v. If radiations of 2000° A fall on the metal then the kinetic energy of the fastest photoelectron is

Question

The work function of metal is 4.2 e v. If radiations of 2000° A fall on the metal then the kinetic energy of the fastest photoelectron is (A) 1.6 × 10-19 J (B) 16 × 1010 J (C) 3.2 × 10-19 J (D) 6.4 × 10-10 J

Tardigrade Admin · Accepted Answer

E0=4.2 eV =4.2 × 1.60 × 10-19 J =6.72 × 10-19 J E=h v=(h c/λ)=(6.6 × 10-34 × 3 × 108/2000 × 10-10) =9.94 × 10-19 J ∴ K E of electron emitted =(9.94-6.72) × 10-19 J=3.22 × 10-19 J

Q. The work function of metal is $4.2 e v$ . If radiations of $200 0^{\circ} A$ fall on the metal then the kinetic energy of the fastest photoelectron is

$1.6 \times 1 0^{- 19} J$

$16 \times 1 0^{10} J$

$3.2 \times 1 0^{- 19} J$

$6.4 \times 1 0^{- 10} J$

Q. The work function of metal is 4.2ev. If radiations of 2000∘A fall on the metal then the kinetic energy of the fastest photoelectron is

1.6×10−19J

16×1010J

3.2×10−19J

6.4×10−10J

E0​=4.2eV=4.2×1.60×10−19J =6.72×10−19J E=hv=λhc​=2000×10−106.6×10−34×3×108​ =9.94×10−19J ∴KE of electron emitted =(9.94−6.72)×10−19J=3.22×10−19J

Q. The work function of metal is $4.2 e v$ . If radiations of $200 0^{\circ} A$ fall on the metal then the kinetic energy of the fastest photoelectron is

$1.6 \times 1 0^{- 19} J$

$16 \times 1 0^{10} J$

$3.2 \times 1 0^{- 19} J$

$6.4 \times 1 0^{- 10} J$