Q.

The electric field in an electromagnetic wave is given by E→=i^ 40cosω(t-zc) NC-1.  The magnetic field induction of this wave is (in SI unit):      [2024]

1 B→=j^ 40cosω(t-zc)  
2 B→=k^40ccosω(t-zc)  
3 B→=i^40ccosω(t-zc)  
4 B→=j^40ccosω(t-zc)  

Ans.

(4)

E→=40cos(ωt-ωcz) NC-1i^

E→ is along +x direction

v→ is along +z direction

and Direction of c^ must be along E→×B→.

So direction of B→ will be along +y and magnitude of B→ will be E0c.

B0=E0c=40c