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Grade 11 Common Test – October 2012

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BISHOPS

GRADE 11 COMMON TEST

Electrostatics, Capacitance, Electricity

October 201242 Marks

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SECTION A

QUESTION 1ONE WORD/TERM ANSWERS

Give one word or phrase that best describes the statement in each question.

1.1The region of space in which a charged particle experiences a force.

1.2The rate of flow of charge.(2 x 1 = 2)

QUESTION 2MULTIPLE CHOICE QUESTIONS

2.1The diagram to the right shows the electric field around two charged objects, A and B. Which statement is correct?

Charge on object A / Magnitude of charge on object A relative to object B
A / positive / A>B
B / positive / A<B
C / negative / A>B
D / negative / A<B

2.2Two charged particles X and Y are placed a distance d apart. X has a charge of q and Y a charge of 3q. The force they exert on each other is F. What would the force become if the charge on object X was increase to 2q and the distance between them increased to 2d?

A½F B F C 2F D 6F

2.3Which statement is NOT true concerning the role of a dielectric material in a commercial capacitor?

AIt weakens the electric field between the plates.

BIt keeps the two metal plates apart when they are rolled up into a cylindrical shape.

CIt increases the capacitance of the capacitor relative to simply having air.

DIt is a good conductor of charge across the capacitor.

2.4What change occurs to the reading on the voltmeter alongside when the switch is closed? (The emf of the battery is 4,5 V and wires have no resistance.)

A4,5 V to 0 V

B stays at 0 V all the time

Cstays at 4,5 V all the time

D0 V to 4,5 V?

(4 x 2 = 8)

SECTION B

3.The battery in the circuit below has an emf of 6 V and an internal resistance of 1 Ω. The ammeter reading is 0,4 A.

3.1Calculate the potential difference across the 2 Ω resistor.(3)

3.2Show that the potential difference across the parallel combination is 4,8 V.(4)

3.3What is the equivalent resistance of the parallel combination?(3)

3.4Calculate the resistance of R.(3)

3.5Calculate the energy lost in the battery as heat every minute.(3)

3.6If the 16 Ω resistor was short circuited using a thick wire connected between X and Y, would the reading on the voltmeter INCREASE, DECREASE OR STAY THE SAME? (1)

[17]

4A capacitor is a device used to store electrical energy. Consider a 5,2 x 10-8F capacitor made of two parallel plates 0,05 mm apart and having a potential difference of 4000 V across them.

4.1Calculate the magnitude of the charge on the plates when fully charged, assuming a vacuum between them. (3)

4.2Calculate the surface area of each plate.(3)

4.3Give an example of the use of a capacitor.(1)

[7]

5.An object with a charge of 5,2 x 10-8 C has a potential energy of 3,0 x 10-3 J at a distance d from a second object with a charge of 6,8 x 10-6C. Calculate the distance d. (4)

[4]

6.1Define potential difference.(2)

6.2A scientist determines by doing an experiment similar to that done by Millikan that the charge on a drop of oil is 1,17 x 10-18 C. Show by simple calculation that this value is not possible. (2)

[4]

END

NAME/NAAM / SYMBOL / VALUE
Acceleration due to gravity / g / 9,8 m·s-2
Coulomb's constant / k / 9,0 x 109 N·m2·C-2
Charge on electron / e- / -1,6 x 10-19 C
Electron mass / me / 9,11 x 10-31 kg
Permittivity of free space / / 8,85 x 10-12 F·m-1

FORCE, WORK, ENERGY AND POWER

/ U
/ w = mg

ELECTROSTATICS

C = / C =

ELECTRIC CIRCUITS

P = VI = I2R = V2
R / W = VIΔt = I2RΔt = V2Δt
R

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