# Calculate the value of induced emf between the ends of an axle of a railway carriage 1.75 m long traveling

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Calculate the value of induced emf between the ends of an axle of a railway carriage 1.75 m long traveling on level ground with a uniform velocity of 50 km per hour. The vertical component of Earth’s magnetic field (Bv) is given to be 5 × 10-5T.

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Data: l = 1.75 m, v = 50 km/h = 50 × $$\frac{5}{18}$$ m/s.
Bv = 5 × 10-5 T
The area swept out by the wing per unit time = 1v.
∴ The magnetic flux cut by the wing per unit time
= $$\frac{d \Phi_{\mathrm{m}}}{d t}$$ = Bv(lv)
=(5 × 10-5)(1.75)(50 × $$\frac{5}{18}$$)= 121.5 × 10-5
= 1.215 mWb/s
Therefore, the magnitude of the induced emf,
|e| =1.215 mV