Worksheets › Class 12 › Electric Charges and Fields
Class 12 Electric Charges and Fields worksheet
CBSE Physics. Coulomb's law, electric field, dipoles, flux and Gauss's law. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
Two point charges of 2 μC and 6 μC are 15 cm apart in air. The force between them is: (k = 9 × 10⁹ N m²/C²)
- 0.048 N
- 48 N
- 72 N
- 4.8 N
Answer
(d) 4.8 N
F = kq₁q₂/r² = 9 × 10⁹ × 2 × 10⁻⁶ × 6 × 10⁻⁶ ÷ (15 × 10⁻²)²
- 2.
Two charges attract each other with a force F. If each charge is made 3 times as large and the distance between them is made 4 times as large, the force becomes:
- (16/9)F
- (3/4)F
- (9/16)F
- (9/8)F
Answer
(c) (9/16)F
F ∝ q₁q₂/r²: × 9 ÷ 16
- 3.
The number of electrons removed from a body that has a charge of +6 μC is: (e = 1.6 × 10⁻¹⁹ C)
- 3.75 × 10¹⁴
- 9.6 × 10⁻²⁵
- 3.75 × 10¹²
- 3.75 × 10¹³
Answer
(d) 3.75 × 10¹³
n = q/e = 6 × 10⁻⁶ ÷ (1.6 × 10⁻¹⁹)
Section B · short answer
- 4.
Charges of −7 μC and −9 μC are at x = 0 and x = 18 cm. Find the net force on a charge of +1 μC at x = 15 cm. (k = 9 × 10⁹ N m²/C²)
Answer
87.2 N towards x = 18 cm
from the first: −2.8 N; from the second: 90 N (positive means towards x = 18 cm)
- 5.
Charges of 3 μC and 48 μC are 40 cm apart. Where between them is the electric field zero?
Answer
8 cm from the 3 μC charge
q₁/x² = q₂/(40 − x)² ⇒ x/(40 − x) = 1/4
Section C · long answer
- 6.
Charges of 3 μC and 4 μC are placed at A and B, each 3 cm from a point C, with CA ⟂ CB. Find the magnitude of the net force on a charge of +4 μC at C. (k = 9 × 10⁹ N m²/C²)
Answer
200 N, at tan⁻¹(4/3) to the line AC
forces 120 N and 160 N at right angles; √(3² + 4²) = 5
Fresh sheets for your child
In the app, every Electric Charges and Fields sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
Coming soon for Android and iPhone.