LIVE Course for free

Rated by 1 million+ students
Get app now
JEE MAIN 2023
JEE MAIN 2023 TEST SERIES
NEET 2023 TEST SERIES
NEET 2023
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
46 views
in Physics by (59.9k points)
closed by
A conductor carries a current of 60μA. If the area of cross-section of the conductor is 30 mm2, then the value of current density is:
1. 0.5 A/m2
2. 2 A/m2
3. 1.5 A/m2
4. 1 A/m2

1 Answer

0 votes
by (110k points)
selected by
 
Best answer
Correct Answer - Option 2 : 2 A/m2

Concept :

Current density:

The amount of charge per unit time that flows through a unit area of a chosen cross-section is known as current density.

\(J =\frac{i}{A}\)

where J is current density, i is current and A is cross-section area.

Calculation:

Given that, i = 60 μA = 60 × 10-6 A, A = 30 mm2

here, I = 60 μA = 50 × 10-6 A

and A = 30 mm² = 30 × 10-6 m²

then, J = I/A = 60 × 10-6 / 30 × 10-6

 J = 2 A/m²

Ohm’s law:

At constant temperature, the potential difference across a current-carrying wire is directly proportional to the current flowing through it.

⇒ V = RI

Electromotive force (e) or e.m.f:

  • The electromotive force (e) or e.m.f. is the energy provided by a cell or battery per coulomb of charge passing through it, it is measured in volts (V).
  • It is equal to the potential difference across the terminals of the cell when no current is flowing i.e., e = IR

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...