A hot filament liberates an electron with zero initial velocity. The anode potential is 1200 V. The speed of the electron when it strikes the anode is

Question

A hot filament liberates an electron with zero initial velocity. The anode potential is 1200 V. The speed of the electron when it strikes the anode is (A) 1.5 × 105 ms-1 (B) 2.5 × 106 ms-1 (C) 2.1 × 107 ms-1 (D) 2.5 × 108 ms-1

Tardigrade Admin · Accepted Answer

(1/2) m v2=V q v=√(2 V q/m) =2.1 × 107 ms -1

Q. A hot filament liberates an electron with zero initial velocity. The anode potential is $1200 V$ . The speed of the electron when it strikes the anode is

$1.5 \times 1 0^{5} m s^{- 1}$

$2.5 \times 1 0^{6} m s^{- 1}$

$2.1 \times 1 0^{7} m s^{- 1}$

$2.5 \times 1 0^{8} m s^{- 1}$

$\frac{1}{2} m v^{2} = V q$
$v = \frac{2 V q}{m}$
$= 2.1 \times 1 0^{7} m s^{- 1}$

Q. A hot filament liberates an electron with zero initial velocity. The anode potential is 1200V. The speed of the electron when it strikes the anode is

1.5×105ms−1

2.5×106ms−1

2.1×107ms−1

2.5×108ms−1