Question

If a metal wire 40cm long is bent to form a rectangle, then what are its dimensions when it’s area is maximum?​

Answer 1

Answer:Given that,

Field of induction B1 = 0.8T

Area A1 = (15×5×10-4) m2

Now, the flux

 ϕ  

1

​  

=75×10  

−4

×0.8

ϕ  

1

​  

=60×10  

−4

Wb

Increases field B2 = 1.4T

Area of square A2 = (10×10×10-4) m2

For square,

Flux

 ϕ  

2

​  

=B  

2

​  

A  

2

​  

 

ϕ  

2

​  

=(1.4×100×10  

−4

)Wb

Change in magnetic flux

 Δϕ=ϕ  

2

​  

−ϕ  

1

​  

 

Δϕ=1.4×100×10  

−4

−0.8×75×10  

−4

 

Δϕ=(140−60)×10  

−4

 

Δϕ=80×10  

−4

Wb

Now, Induced emf is

 e=  

Δt

Δϕ

​  

 

e=  

0.5

80×10  

−4

 

​  

 

e=160×10  

−4

 

e=1.6×10  

−2

,volt

Hence, the e.m.f induced in the frame is e=1.6×10  

−2

 volt.

Step-by-step explanation: