Test: Magnetic Effects of Electric Current - 4 - UPSC MCQ

A fuse is used to break the circuit,in order to protect the electrical appliances from damage. In case of overcurrent a fuse melts and breaks the circuit and stops the current flowing through the components. A fuse is made up of a thin material which has a low melting point.

The correct option is D.
 In this case when the main switch of the house is switched off it would disconnect the live wire and the neutral wire.

Every fuse has given particular thickness to with stand particular electric current strength, the current value 8A means that the fuse will melt or will burn out if the current passing through the fuse exceeds 8A , other than that the fuse will work fine even if the current supplied lower than that of 8A .

According to international color coding system in Old colors red is live ( or phase) black is neutral, green/ yellow is earth.

The magnetic field produced by a current carrying solenoid is similar to the magnetic field produced by a bar magnet. The magnetic field lines inside the solenoid are in the form of parallel straight lines and along the axis of solenoid.

Among given options half revolution is the right answer.

The current induced by the magnetic field in the rectangular coil made up of copper wire is being turned in order to rotate in the magnetic field, at every turn, the direction of induced current changes and being a vector quantity, induced current changes every half revolution.
 

The field lines inside the solenoid are in the form of parallel straight lines. For a solenoid, the field has to be uniform as a function of position along the axis, since every point along the length is the same as every other point. This indicates that the magnetic field is uniform inside the solenoid.
Hence magnetic field is the same at all points inside the solenoid. 

Because both of them have current flowing through them in equal ratio. i1: i2 = mag1: mag2

Magnetic field produced is directly proportional to the current flowing and inversely proportional to the distance from the conductor. Since current flowing in both conductors is same only distance matters here. Since field is inversely proportional to distance ; 
B(A) / B(B)  = d(B) / d ( A) = 0.2/0.5 
=>  0.4 

When a conductor carries current it emits magnetic field around it . By the right-hand rule, a current out of the page in a field up gives a force to the left. Two parallel wires carrying currents in the same direction attract one another; wires with currents going in opposite directions repel.

If the switch is placed in the neutral wire, the electrical appliance is still connected to the high voltage live wire even when the switch is opened.)
This may cause the user to get an electric shock if he touches the live wire.
That’s why the switches are put in the live wire.

Each moving charged particle in a magnetic field experiences a force. The direction of force experienced by a positive charge is given by Fleming's left hand rule. The force acting on the proton would change both velocity and momentum. 

The correct answer is A as Here the direction of current toward west and towards north .So by Fleming left hand rule the direction of magnetic field is upward. the rule used in Fleming left hand rule which states that if we stretch our thumb forefinger and middle figure of our left hand perpendicular to each other in such a way that forefinger points the direction of magnetic field and middle figure points the direction of current and middle figure points the direction of current then thumb will represent the direction of force.