 JEE Mains Previous Years Questions with Solutions

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1

AIEEE 2011

This question has Statement - $1$ and Statement - $2$. Of the four choices given after the statements, choose the one that best describes the two statements.
Statement -$1$ : Sky wave signals are used for long distance radio communication. These signals are in general, less stable then ground wave signals.
Statement -$2$ : The state of ionosphere varies from hour to hour, day to day and season to season.
A
Statement - $1$ is true, Statement - $2$ is true, Statement - $2$ is the correct explanation of Statement - $1$.
B
Statement - $1$ is true, Statement - $2$ is true, Statement - $2$ is not the correct explanation of Statement - $1$.
C
Statement - $1$ is false, Statement - $2$ is true
D
Statement - $1$ is true, Statement - $2$ is false.

Explanation

For long distance communication, sky wave signals are used.

Also, the state of ionosphere varies every time. So, both statements are correct.
2

AIEEE 2003

Consider telecommunication through optical fibres. Which of the following statements is not true?
A
Optical fibres can be of graded refractive index
B
Optical fibres are subject to electromagnetic interference from outside
C
Optical fibres have extremely low transmission loss
D
Optical fibres may have homogeneous core with a suitable cladding.

Explanation

Optical fibres form a dielectric wave guide and are free from electromagnetic interference or radio frequency interference.