FieldsIB Physics SL: Topic test

20 questions, 54 marks

IB Physics SL

Fields topic test

Total 54 marks

Name

Class

Date

1
A planet orbits its star in a circular orbit of radius 2.2 × 10¹¹ m, with an orbital period of 685 days. The mass of the star is 1.8 × 10³⁰ kg.
(a)
What is the gravitational field strength due to the star at the planet's orbital radius?
[1 mark]
A2.48 × 10⁻³ N kg⁻¹
B1.24 × 10⁻³ N kg⁻¹
C4.96 × 10⁻³ N kg⁻¹
D5.46 × 10⁸ N kg⁻¹
(b)
What is the orbital speed of the planet?
[1 mark]
A3.72 × 10³ m s⁻¹
B2.34 × 10⁴ m s⁻¹
C4.67 × 10⁴ m s⁻¹
D2.02 × 10⁹ m s⁻¹
(c)
Determine the centripetal acceleration of the planet, and comment on how this compares with your answer to (a).
[2 marks]
Total for question 1: 4 marks
2
Two point charges, +4.0 μC and −6.0 μC, are fixed 0.50 m apart in air.
(a)
What is the magnitude of the electrostatic force between the two charges?
[1 mark]
A0.432 N
B3.456 N
C0.864 N
D0.576 N
(b)
What is the magnitude of the resultant electric field at the midpoint between the two charges?
[1 mark]
A2.88 × 10⁵ N C⁻¹
B8.64 × 10⁵ N C⁻¹
C3.60 × 10⁵ N C⁻¹
D1.44 × 10⁶ N C⁻¹
(c)
A small test charge of +2.0 nC is placed at the midpoint. Determine the magnitude of the force on it.
[2 marks]
Total for question 2: 4 marks
3
Two horizontal parallel plates, 4.0 cm apart, have a potential difference of 800 V between them, with the upper plate positive. A small charged sphere of mass 6.0 × 10⁻¹⁵ kg and charge −5.0 × 10⁻¹⁸ C is held in the field between the plates.
(a)
Determine the electric field strength between the plates, and the electric force on the sphere, stating its direction.
[3 marks]
(b)
Compare the electric force on the sphere with the gravitational force acting on it, and determine the resultant (net) force on the sphere, including its direction.
[4 marks]
Total for question 3: 7 marks
4
A satellite of mass 650 kg orbits Earth in a circular orbit at an altitude of 1200 km above the Earth's surface. Earth's radius is 6.37 × 10⁶ m and its mass is 5.97 × 10²⁴ kg.
(a)
Determine the gravitational field strength at the satellite's orbital radius, and hence its orbital speed and period, given that gravity provides the centripetal force for the orbit.
[6 marks]
(b)
A second satellite orbits at a lower altitude of 400 km. Explain how the gravitational field strength, orbital speed and orbital period at this altitude compare with your answers to (a), and determine the new orbital period.
[6 marks]
Total for question 4: 12 marks
5
The gravitational field strength at the surface of a moon is 1.6 N kg⁻¹. The moon has a radius of 1.74 × 10⁶ m.
(a)
What is the mass of the moon?
[1 mark]
A2.91 × 10²³ kg
B7.26 × 10²² kg
C3.63 × 10²² kg
D1.82 × 10²² kg
(b)
What is the gravitational field strength at a distance from the moon's centre equal to twice its radius (i.e. one radius above the surface)?
[1 mark]
A0.400 N kg⁻¹
B0.800 N kg⁻¹
C6.40 N kg⁻¹
D0.533 N kg⁻¹
(c)
Determine the weight of a 900 kg lander at the surface of the moon.
[2 marks]
Total for question 5: 4 marks
6
A straight wire of length 0.80 m carries a current of 6.0 A and is placed perpendicular to a uniform magnetic field of flux density 0.25 T.
(a)
What is the magnitude of the force on the wire?
[1 mark]
A1.875 N
B4.80 N
C0.200 N
D1.20 N
(b)
The current in the wire is doubled and the wire is now placed at 30° to the field instead of perpendicular to it. What is the new force on the wire?
[1 mark]
A2.40 N
B2.08 N
C1.20 N
D0.600 N
(c)
A second wire, carrying a current of 4.0 A in the same direction, is placed parallel to the original wire (now carrying its original current of 6.0 A) at a separation of 5.0 cm. Determine the force per unit length between the two wires.
[2 marks]
Total for question 6: 4 marks
7
A fixed point charge of +8.0 μC is located in a vacuum. A small test charge of −4.0 nC and mass 2.5 × 10⁻¹² kg is placed 0.60 m from the fixed charge and released from rest.
(a)
Determine the magnitude and direction of the electric force on the test charge when it is released.
[3 marks]
(b)
Determine the initial acceleration of the test charge, and explain, without further calculation, how this acceleration changes as the test charge moves closer to the fixed charge.
[4 marks]
Total for question 7: 7 marks
8
A beam of positive ions, each of charge +1.6 × 10⁻¹⁹ C and mass 3.3 × 10⁻²⁷ kg, enters horizontally at 5.0 × 10⁵ m s⁻¹ midway between two horizontal parallel plates of length 12 cm, separated by 3.0 cm. A potential difference of 150 V is applied between the plates (upper plate negative), pushing the positive ions upward.
(a)
Determine the electric field strength between the plates, the force on each ion, and its vertical acceleration.
[6 marks]
(b)
Determine the vertical deflection of the ion beam as it leaves the plates, and state, with a reason, whether the beam clears the plates.
[6 marks]
Total for question 8: 12 marks

End of questions