##### TMA

# TMA3/PHY102 – Electricity, Magnetism and Modern Physics

## TMA Quiz Questions

TMA: TMA3/PHY102

PHY102 – Electricity, Magnetism and Modern Physics

Mr. Ibanga Efiong (eibanga@noun.edu.ng )

1 In the circuit shown, each of the cells has an emf of 2V and internal resistance of

0:1Ω

0.1Ω

. Find the current in through the

0.5Ω

Click here to see exhibit

A. 0.13A

B. 3.45A

C. 1.27A

D. 2.44A

2 Calculate the electric field everywhere outside of a very long rod, radius R and charged to a uniform linear charge density

λ

.

A. E⃗ =λπrϵ0r^

B. E⃗ =λπϵ0ln1rr^

C. E⃗ =λ2πrϵ0r^

D. E⃗ =λ2πϵ0ln1rr^

3 Kirchhof’s junction rule is statement of conservation of ———–

A. mass

B. energy

C. charge

D. momentum

4 A galvanometer of resistance

120Ω

a full scale deflection with a current of 0.0005A. How would you convert it to an ammeter that reads a maximum current of 5A?

A. connect

2000Ω

in parallel to it

B. connect

200.12Ω

in series to it

C. connect $20.10\Omega$$ in series to it

D. connect

0.012Ω

in parallel to it

5 A galvanometer with coil resistance

12.0Ω

shows full scale deflection for a current of 2.5mA. How would you convert it into a voltmeter of range 0 to 10.0V?

A. 3988Ω

in series

B. 0.43Ω

in parallel

C. Ω

in parallel

D. 1.62Ω

in series

6 A series circuit consisting of an uncharged 42ÖF capacitor and

10MΩ

resistor is connected to 100V power source. What are the current in the circuit and the charge on the capacitor after one time constant?

A. 3.7μA

and

126μC

B. 4.6μA

and

221μC

C. 7.2μA

and

100μC

D. 1.3μA

and

52μC

7 A capacitor of

2.0μF

is connected to a battery of 2.0V through a resistance of

10kΩ

. What is the initial current in the circuit and the current after 0.02s?

A. 0.5μA

and 0.074mA

B. 7.4A and 5.0mA

C. 0.2μA

and 0.074mA

D. 6.2μA

and 7.04mA

8 A conductor 2cm long carrying a current of 8A lies at right angles to a magnetic field of which the flux density is 1.0T. Calculate the force exerted on the conductor

A. 0.20N

B. 0.16N

C. 0.25N

D. 0.45N

9 One end of a simple rectangular wire-loop current balance is inserted into a solenoid. A force of

3.0×10−3

N is found to act on this end when a current of 2.0A is flowing in it. If the length of the conductor forming the end of the the wire-loop is 0.

A. 0.043T

B. 0.26T

C. 0.43T

D. 0.015T

10 A staight wire 1.0m long carries a currernt of 100A at right-angles to a uniform magnetic field of 1.0T. Find the mechanical force on the wire and the power required to move it at 15m/s in a plane at right-angles to the field.

A. 100N and 1.5kW

B. 200N and 2.5kW

C. 300N and 1.4kW

D. 200N and 2.7kW

11 A rectangular coil of dimensions 20cm by 15cm lies with its plane parallel to a magnetic field of

0.5W/$m2

. The coil, carrying a current of 10A experiences a torque of 4.5Nm in the field. How many loops has the coil?

A. 100

B. 60

C. 30

D. 20

12 An electric feild of 50kV/m is perpendicular to a magnetic field 0.25T. What is the velocity of a charge whose initial of motion is perpendicular to both fields and which passes through the fields undeflected?

A. 3×103

m/s

B. 2×105

m/s

C. 4×107

m/s

D. 5×104

m/s

13 A proton is accelerated through a potential difference of 100V and the enters a region in which it is moving perpendicular to a magnetic field of flux density 0.20T. Find the radius of the circular path in which it will travel.

A. 0.9km

B. o.7km

C. 0.3km

D. 0.5km

14 An electron enters a uniform magnetic field 0.20T at an angle of

30o

the field. Determine the pitch of the helical path assuming its speed is

3×107

m/s

A. 90.6m

B. 37.8m

C. 56.1m

D. 46.5m

15 A positive ion passes through an electric and magnetic fields which are mutually perpendicular. The electric field strength is 20.0kV/m while the magnetic flux density is 0.40T. At what speed will the ion pass through undeflected?

A. 6.0×104

m/s

B. 5.0×104

m/s

C. 7.0×104

m/s

D. $8.0\times10^{4}$$m/s

16 For how long must a steady current of 2A flow through a copper voltameter to deposit 10À3kg of copper? Z for coper is 0.000329g/C

A. 42.1min

B. 22.6min

C. 30.2min

D. 25.3min

17 An ammeter is suspeted of giving inaccurate readings. In order to confirm the readings, the ammeter is connected to a silver votltameter in series and a steady current is passed for one hour. The ammeter reads 0.56A and 2.0124g of silver is deposited. Wha

A. 0.06A

B. 0.11A

C. 1.1A

D. 6.0A

18 The magnetic flux through each loop of a 35-loop coil is given by (3:6tÀ0:71t3)Â10À2Tm2, where the time is in seconds. Determine the induced emf at t=5.0s.

A. 6.17V

B. 14.43V

C. 17.49V

D. 9.17V

19 A single turn coil of cross-sectional area 7.2cm^2 is in the a magnetic field of flux desity 0.45T. The field which is perpendicular to the coil, is steadily reduced to 0.0T in 5s. Calculate the induced emf.

A. 0:72ÖV

B. 0:52ÖV

C. 0:47ÖV

D. 0:65ÖV

20 What is the self – inductance of an air-core solenoid, 1m long and 0.05m in diameter, if it has 1400 turns?

A. 5.23mH

B. 4.84mH

C. 3.63mH

D. 2.42mH

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