Electricity & Magnetism MCQs with Answers

In a dry cell, is used as the cathode.

• A.Zinc (Zn)
• B.Copper (Cu)
• C.Carbon (C)
• D.Lead (Pb)

For an induction machine rated at 150 V and 3.5 kW, with 90% efficiency, if the armature current is increased to 200% of its rated value, the machine's rated current would be ?

• A.Equal to the rated current
• B.2 times the rated current
• C.Half of the rated current
• D.4 times the rated current

Which impurity is added to form an N-type semiconductor?

• A.Trivalent
• B.Monovalent
• C.Divalent
• D.Pentavalent

The equivalent capacitance of combination increases if

• A.Capacitors are in parallel combination
• B.Capacitors are in series combination
• C.Capacitors are identical and in series
• D.None of these

Which is used for on and off?

• A.Capacitor
• B.Fuse
• C.Resistor
• D.Switch

Which of the following statements is true?

• A.North pole attracts South pole
• B.North pole attracts North pole
• C.South pole attracts South pole
• D.Like poles attract each other

Insulating materials are _ in nature.

• A.Semiconductor
• B.Conductive
• C.Magnetic
• D.Dielectric

If the current in a wire which is placed perpendicular to a magnetic field increases, the force on the wire ?

• A.Remains the same
• B.Decreases
• C.Increases
• D.Becomes zero

Fire Alarm don't work in which condition?

• A.In absence of oxygen
• B.In smoky environment
• C.In presence of carbon dioxide
• D.All of these

What is the self-inductance of a coil if the current changes from 5A to 0A in five seconds and the induced voltage is 500 volts?

• A.100 Henry
• B.250 Henry
• C.500 Henry
• D.1000 Henry