Advertisements
Advertisements
Question
Options
increases
decreases
remains the same
- increases or decreases
Advertisements
Solution
When the resistance of a conductor increases, the current decreases.
APPEARS IN
RELATED QUESTIONS
An electromagnet does not attract a piece of iron.
Name the scientist who discovered the magnetic effect of current.
Fill in the following blank with suitable words:
If a coil is viewed from one end and the current flows in an anticlockwise direction, then this end is a ........... pole.
Describe some experiment to show that the magnetic field is associated with an electric current.
The direction of current flowing in the coil of an electromagnet at its two ends X and Y are as shown below:
What is the polarity of end X?
What is the polarity of end Y?
Name and state the rule which you have used to determine the polarities.
Which way does the wire in the diagram below tend to move?
When the switch S is closed in the figure given below, the pointer of the galvanometer moves to the right.
If S is kept closed, will the pointer:
(a) return to zero?
(b) stay over on the right?
(c) move to the left and stay there
(d) move to and fro until S is opened
A coil is connected to a galvanometer. When the N-pole of magnet is pushed into the coil, the galvanometer deflected to the right. What deflection, if any, is observed when:
the N-pole is removed?
(b) State whether the following statements are true or false:
(i) Magnetic poles exist in pairs.
(ii) Global warming is a desirable aspect of the intensified greenhouse effect.
Draw a neat labelled diagram to show the magnetic effect of electric current.
Identify the given figure, write the labels of it.

If the key in the given arrangement is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane ABCD, the lines are ____________.

What is that instrument which can detect the presence of electric current in a circuit?
A magnetic compass shows a deflection when placed near a current carrying wire. How will the deflection of the compass get affected if the current in the wire is increased? Support your answer with a reason.
Paheli does not have a night lamp in her room. She covered the bulb of her room with a towel at the night to get dim light. Has she taken the right step? Give one reason to justify your answer.
Why do we cover plug pin holes which are within the reach of children with cellotape or a plastic cover when not in use?
A student was asked to perform an experiment to study the force on a current carrying conductor in a magnetic field. He took a small aluminium rod AB, a strong horse shoe magnet, some connecting wires, a battery and a switch and connected them as shown. He observed that on passing current, the rod gets displaced. On reversing the direction of current, the direction of displacement also gets reversed. On the basis of your understanding of this phenomenon, answer the following questions:

- Why does the rod get displaced on passing current through it?
- State the rule that determines the direction of the force on the conductor AB.
-
- If the U-shaped magnet is held vertically and the aluminium rod is suspended horizontally with its end B towards due north, then on passing current through the rod from B to A as shown, in which direction will the rod be displaced?
- Name any two devices that use current carrying conductors and magnetic fields.
OR
Draw the pattern of magnetic field lines produced around a current carrying straight conductor held vertically on a horizontal cardboard. Indicate the direction of the field lines as well as the direction of current flowing through the conductor.
Using an electromagnet, you can make a working model of a railway signal as shown in figure.

