Two parallel rails of a railway track insulated from each other and with the ground are connected to a millivoltmeter. The distance between the rails is 1 m. A train is travelling with a velocity of 72 kmh -1 along the track. The reading of the millivoltmeter (in mV ) is (vertical component of the earth's magnetic induction is 2 × 10-5 T )

Question

Two parallel rails of a railway track insulated from each other and with the ground are connected to a millivoltmeter. The distance between the rails is 1 m. A train is travelling with a velocity of 72 kmh -1 along the track. The reading of the millivoltmeter (in mV ) is (vertical component of the earth's magnetic induction is 2 × 10-5 T ) (A) 1.44 (B) 0.72 (C) 0.4 (D) 0.2

Tardigrade Admin · Accepted Answer

Induced emf, ε=B v l v= text velocity of train =72 × (5/18)=20 ms -1 Induced emf, ε=2 × 10-5 × 20 × 1 =2 × 10-5 × 20=40 × 10-5 V =40 × 10-2 mV =0.4 mV

$1.44$

$0.72$

$0.4$

$0.2$

Induced emf, $ε = B v l$
$v = velocity of train = 72 \times \frac{5}{18} = 20 m s^{- 1}$
Induced emf, $ε = 2 \times 1 0^{- 5} \times 20 \times 1$
$= 2 \times 1 0^{- 5} \times 20 = 40 \times 1 0^{- 5} V$
$= 40 \times 1 0^{- 2} mV = 0.4 mV$

1.44

0.72

0.4

0.2

Induced emf, ε=Bvl v= velocity of train =72×185​=20ms−1 Induced emf, ε=2×10−5×20×1 =2×10−5×20=40×10−5V =40×10−2mV=0.4mV

$1.44$

$0.72$

$0.4$

$0.2$

Induced emf, $ε = B v l$
$v = velocity of train = 72 \times \frac{5}{18} = 20 m s^{- 1}$
Induced emf, $ε = 2 \times 1 0^{- 5} \times 20 \times 1$
$= 2 \times 1 0^{- 5} \times 20 = 40 \times 1 0^{- 5} V$
$= 40 \times 1 0^{- 2} mV = 0.4 mV$