Magnetism and Inductance - All sections - units, symbols, force and emf, circuit calculations, reactance, self and mutual inductance, magnetic flux, types of equipment - 10 random questions from a large bank.
The current in a coil changes from 5 amperes to 2 amperes in 50mS and induces a voltage of 30v into the coil. Calculate the value of the Inductance of the coil.
0.1H
0.5H
1.1H
3H
Calculate the Inductive Reactance of a coil with inductance of 0.1H, connected to a 50Hz AC supply.
314.2 ohms
0.3142 ohms
3.142 ohms
31.42 ohms
What is the effect of an Inductive (coil) load on an AC supply
power factor lag
power factor lead
power factor unity
no effect
identify the unit of measure for Inductance
Farad
Weber
Tesla
Henry
identify the symbol for Inductance
L
H
B
M
identify the symbol for Mutual Inductance
I
M
B
L
a conductor 30m long is placed in a Magnetic Flux Density of 0.4T. Calculate the force with which it moves if 8A flows in the conductor
96N
176N
56N
226N
a conductor 45m long moves with a force of 235N when 12A flows in the conductor. Calculate the Magnetic Flux Density
435mT
435mWb
0.044Wb
0.044T
a 50m long conductor moves with a force of 420N when 14A flows through it when in a magnetic flux of 0.6T. Calculate the mass that could be moved
66.6
420
42.8
96
identify the correct formula
I= F/BL
F= BIv
emf = BIL
emf = BI/v
identify the correct formula
emf= BLv
F= BLv
emf = BIL
emf = BI/L
a conductor 23m long is moved at 15m/s inside a magnetic flux density of 0.4T calculate the emf produced
303v
230v
95v
138v
a conductor has 60v emf induced into it when a conductor 26m long is moved inside a magnetic flux density of 100mT. Calculate the velocity of the conductor
23.1 m/s
231 m/s
2.31 m/s
0.321 m/s
identify the correct unit of measure for e.m.f
weber
watts
henry
volts
which one of the following would be classed as an inductive load
ballast
capacitor
heater
lamp
which one of the following makes use of 'self inductance'
choke
transformer
electric welder
p.f correction capacitor
which one of the following makes use of 'mutual inductance'
110v site transformer
ballast
choke
electro-magnet
a coil has 125 turns and a magnetic flux of 300mWb, calculate the Inductance value when 5A flows in the coil
0.065
3.35
7.5
9
Calculate the magnetic flux density for a coil with magnetic flux = 300µWb and a core area of 105mm2
31500 Tesla
2.86 Tesla
0.35 Tesla
405 Tesla
A coil has a magnetic flux of 100 µWb when the magnetic flux density is 400mT. Calculate the area of the core and convert your answer into mm2.
40mm2
25mm2
250mm2
500mm2
4A coil has a magnetic flux density of 1.2T when a coil is connected with a 100mm2 core. Calculate the Magnetic Flux.
333.3µWb
83.33µWb
1200µWb
120µWb
A magnetic flux in a coil of 2200turns changes from 0.8mWb to 0.4mWb in 65mS. Calculate the back e.m.f induced into the coil
-56.5v
-44.5v
-13.5v
-11.5v
A coil induces a back e.m.f of 210v when the magnetic flux changes from 100mWb to 30mWb. The coil has 4100turns. Calculate how quickly the magnetic flux changes.
45.55 secs
23.86 secs
5.42 secs
1.39 secs
A coil has 90turns and a magnetic flux of 60mWb. If 6A passes through the coil calculate the inductance of the coil.
0.9 H
2.1 H
14.8 H
0.2 H
A coil has a magnetic flux of 88mWb and an inductance of 2.86H when 1.2A flows. Calculate the number of turns on the coil required to achieve this.
100 turns
39 turns
21 turns
302 turns
A transformer has a mutual inductance of 0.6H. If current in the primary coil changes from 10A to 3A calculate the change in the magnetic flux .
10.8 Wb
4.2 Wb
0.3 Wb
15.5 Wb
A coil has an inductance of 1500mH. If current in the coil changes from 0.8A to 0.2A in 11ms, calculate the e.m.f induced back into the coil.