Coulomb's law between two point charges is F = kQ₁Q₂/r² and electric field strength is force per unit charge, so this Year 13 sheet pairs the electric force law with its field definition. The key records F = BIL where a wire meets a magnetic field.
Key Takeaways
Coulomb's law is F = kQ₁Q₂/r² (Q1).
Electric field strength is force per unit charge (Q2).
The key records F = BIL for a current-carrying wire in a magnetic field.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.Coulomb's law for the force between two point charges Q₁ and Q₂ separated by r is...
(a) F = kQ₁Q₂/r(b) F = kQ₁Q₂/r²(c) F = kQ₁Q₂r(d) F = k(Q₁ + Q₂)/r²
2.Electric field strength at a point is defined as...
(a) force per unit charge(b) force per unit mass(c) potential per unit charge(d) charge per unit volume
3.Electric field lines point from...
(a) negative to positive charge(b) positive to negative charge(c) north to south(d) the centre outwards in all directions
4.The force on a charge q in a uniform electric field of strength E is...
(a) F = Eq²(b) F = q/E(c) F = Eq(d) F = E/q
5.The force on a straight wire of length L carrying current I perpendicular to a magnetic field of flux density B is...
(a) F = BIL(b) F = BI/L(c) F = BL/I(d) F = B/IL
6.Fleming's left-hand rule gives the direction of...
(a) the force on a current-carrying conductor in a magnetic field(b) the induced e.m.f. in a moving wire(c) the field around a straight wire(d) the current in a solenoid
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.State Coulomb's law.
8.Define electric field strength and give its SI unit.
9.Define magnetic flux density in terms of the force on a current-carrying conductor.
10.State Fleming's left-hand rule.
11.What is the force on a charged particle moving parallel to a magnetic field?
12.Define potential difference in terms of work done and charge.
13.What is meant by a uniform electric field?
14.Describe the path of a charged particle moving at right angles to a uniform magnetic field, and explain why it follows that path.
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.Two point charges of 2×10⁻⁶ C and 3×10⁻⁶ C are separated by 0.5 m. Using F = kQ₁Q₂/r² with k = 9×10⁹ N m² C⁻², calculate the force between them.
16.A uniform electric field is produced between two parallel plates separated by 2×10⁻³ m with a potential difference of 200 V. Using E = V/d, calculate the field strength.
17.A charge of 1.6×10⁻¹⁹ C is placed in a field of strength 2×10⁵ N C⁻¹. Using F = Eq, calculate the force on it.
18.An electron of charge 1.6×10⁻¹⁹ C is accelerated from rest through a potential difference of 100 V. Using W = qV, calculate the kinetic energy gained.
19.A wire of length 0.4 m carries a current of 3 A perpendicular to a magnetic field of flux density 0.2 T. Using F = BIL, calculate the force on the wire.
20.A proton of mass 1.67×10⁻²⁷ kg and charge 1.6×10⁻¹⁹ C moves at 2×10⁶ m s⁻¹ at right angles to a magnetic field of 0.5 T. Using r = mv/Bq, calculate the radius of its circular path.
Answer Key
1. b) F = kQ₁Q₂/r²
2. a) force per unit charge
3. b) positive to negative charge
4. c) F = Eq
5. a) F = BIL
6. a) the force on a current-carrying conductor in a magnetic field
7. Refer to solution guide.
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End of Worksheet
People Also Ask
What is Coulomb's law?
F = kQ₁Q₂/r², option (b) in this worksheet (Q1).
What is electric field strength?
Force per unit charge, option (a) in this worksheet (Q2).
What is the magnetic force on a current-carrying conductor?
F = BIL, from the answer key on this page.
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