3642

Physics Current Electricity Level: University

Measurement
A galvanometer is to be turned into a voltmeter that deflects full scale for a  potential difference of 100.0V. What size resistor should be places in series with the galvanometer if it has an internal resistance of 75 Ohm and deflects full scale for a current of 2.0 mA?

2088

Physics Magnetism,Magnetic Effects Of Current Level: High School

Magnetic Effect of Current

Calculate the magnitude of the magnetic force on a 160-m length of straight wire stretched between two towers carrying a 150-A current . The earth's magnetic field of 5.0*10^-5 T makes an angle of 65 degree with the wire .

1996

Physics Current Electricity Level: High School

Two scales on a voltmeter measure voltage up to 20.0 and 30.0 V , respectively . The resistance connected in a series with the galvanometer is 1680 Ohm for the 20 V scale , and 2930 Ohm for the 30 V scale . Determine the coil resistance and the full scale current of the galvanometer that is used in the voltmeter .

535

Physics Magnetism,Magnetic Effects Of Current Level: High School

A circular loop carrying a current of 1.0 A is oriented in a magnetic field of 0.35 T . The loop has an area of 0.24 m2 and is mounted on an axis , perpendicular to the magnetic field , which allows the loop to rotate . If the plane of the loop is oriented parallel to the field , What torque is created by the interaction of the loop current and field ?

a. 5.8 N.m

b. 0.68 N.m

c. 0.084 N.m

d. 0.017 N.m

534

Physics Magnetism,Magnetic Effects Of Current Level: High School

Which of the following devices makes use of an electromagnet ?

A. loudspeaker

B. galvanometer

C. both A and B

D. None of the above

533

Physics Magnetism,Magnetic Effects Of Current Level: High School

A copper wire of length 25 cm is in a magnetic field of 0.20 T . If it has a mass of 10 g . What is the minimum current through the wire that would cause a magnetic force equal to its weight ?

a. 1.3 A

b. 1.5 A

c. 2.0 A

d. 4.9 A

532

Physics Magnetism,Magnetic Effects Of Current Level: High School

An electron moves through a region of crossed electric and magnetic field . The electric field E = 2000 V/m and is directed straight down . The magnetic field B = 0.80 T and is directed to the left . For what velocity v of the electron into the paper will the electric force exactly cancel the magnetic force?

a. 2500 m/s

b. 4000 m/s

c. 5000 m/s

d. 8000 m/s

531

Physics Current Electricity Level: High School

A proton moving at a speed of 3.8 x 106 m/s cuts across the lines of a magnetic field at an angle of 70 degree. The strength of the field is 0.25 x 10-4 T. What is the magnitude of the force acting on the proton ? (qp = 1.6 x 10 – 19C)

a. 5.1 x 10-18 N

b. 9.0 x 10-18 N

c. 1.4 x 10 -17 N

d. 2.3 x 10-17 N

530

Physics Magnetism,Magnetic Effects Of Current Level: High School

Assume that a uniform magnetic field is directed into this page . If an electron is released with an initial velocity directed from the bottom edge to the top edge of the page, which of the following describes the direction of the resultant force acting on the electron ?

a. out of the page

b. to the right

c. to the left

d. into the page

529

Physics Current Electricity Level: High School

The force on a charged particle created by its motion in a magnetic field is maximum at what angle between the particle velocity and field ?

a. zero

b. 180 degree

c. 90 degree

d. 45 degree