# Mechatronics Questions and Answers – Electrical Actuating Systems – Solenoids

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This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “ Electrical Actuating Systems – Solenoids”.

1. Which type of coil is a solenoid?
a) Electromagnetic
b) Electrical
c) Mechanical
d) Chemical

Explanation: Solenoid is an electromagnetic coil. When an electric current is supplied to the solenoid, the magnetic field is induced in it and due to this the spool shifts to the selected position.

2. Iron is used in solenoids for ____
a) increasing the magnetic field strength
b) increasing the electric field strength
c) decreasing the magnetic field strength
d) decreasing the electric field strength

Explanation: The iron is used in solenoids for increasing the magnetic field strength. This is because of the ferromagnetic property of the iron. All ferromagnetic materials help to increase the magnetic property of an object.

3. The number of turns of the solenoid is inversely proportional to the magnetic field.
a) True
b) False

Explanation: The mentioned statement is false as the number of turns of the solenoid is directly proportional to the magnetic field. So as the number of turns increases, the magnetic field of the solenoid will increase accordingly and as it decreases, the magnetic field turns weak.

4. What is the relation between the current and the magnetic field?
a) Directly proportional
b) Inversely proportional
c) Independent of each other
d) No relation

Explanation: The relation between the current and magnetic field of a solenoid is that the current and the magnetic field are directly proportional to each other. The magnetic field increases or decreases according to the increase or decrease in the value of the current.

5. What is the relation between the magnetic field and the number of turns of a solenoid?
a) Inversely proportional
b) Directly proportional
c) Independent of each other
d) No relation

Explanation: The magnetic field of a solenoid is directly proportional to the number of turns in the solenoid. Dues the magnetic field of the solenoid increases and decreases with the increase and decrease in the number of turns respectively.

6. The magnetic field inside a solenoid is uniform.
a) True
b) False

Explanation: The magnetic field produced inside a solenoid is stronger than the magnetic field outside it, and it is uniform. The presence of a stronger magnetic field inside is due to the presence of the current inside the solenoid.

7. What is the direction of the magnetic field with respect to the current of a solenoid?
a) Parallel
b) Perpendicular
c) No fixed direction
d) Reverse direction

Explanation: The direction of the magnetic field generated in a solenoid acts always perpendicular to the direction of the applied current. The relation between the current and magnetic field of a solenoid is that the current and the magnetic field are directly proportional to each other.

8. Which among the following are not the applications of a solenoid?
a) Electromagnets
b) Medical
c) Industries
d) Vessels

Explanation: Based on its property’s solenoids have very vast applications. Some of the operations include used in electromagnets, medical, valves, industries etc. The best example is the car starting system where the transfers the current to different parts of the motor.

9. What is the formula for the turn density of a solenoid?
a) n=N/L
b) N=n/l
c) n=N.l
d) N=nN/l

Explanation: The formula for the turn density of a solenoid is (n= N/L) where n is the turn density, l is the length of the solenoid and N is the number of turns of the solenoid. The other options mentioned are not the appropriate answers.

10. How can we increase the magnetic field strength of a solenoid?
a) By increasing current
b) Removing iron from the field
c) By decreasing the current
d) By decreasing the number of turns 