Magnetic Effects of Electric Current
- What is the function of an earth wire? Why is it necessary to earth metallic appliances? The metallic body of electric appliances is connected to the earth by means of earth wire so that any leakage of electric current is transfe... 1
- When does an electric short circuit occur? If the insulation of the wires used in the circuit is damaged or the appliance used is faulty due to which the live wire and the neutral wir... 1
- Explain the underlying principle and working of an electric generator by drawing a labelled diagram. Principle: An electric generator works on the principle of electromagnetic induction phenomenon. According to it, whenever a coil is rotated... 1
- State the rule to determine the direction of a (i) magnetic field produced around a straight conductor-carrying current, (i) Maxwell's right hand thumb rule (ii) Fleming's left hand rule (iii) Fleming's right hand rule 1
- Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current Two circular coils A and B are placed close to each other. When the current in coil A is changed, the magnetic field associated with it also... 1
- A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (i) The needle of the galvanometer shows a momentary deflection in a particular direction. (ii) The needle of the galvanometer shows a momen... 1
- Name some devices in which electric motors are used? Some devices in which electric motors are Water pumps, Electric fans, Electric mixers and Washing machines. 1
- Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split ring https://lh3.googleusercontent.com/-QCgE9gUPJaU/YbgHE65MlaI/AAAAAAAAC78/XGDS2ET9w7IMJWW4uuiFe0KqFc7zJt0QQCNcBGAsYHQ/image.png Principle: It w... 1
- Imagine that you are sitting in a chamber with your back to one wall. The direction of the magnetic field is vertically downwards. The direction of current is from the front wall to the back wall because negati... 1
- When is the force experienced by a current-carrying conductor placed in a magnetic field largest? The force experienced by a current-currying conductor is the maximum when the direction of current is perpendicular to the direction of the... 1
- How does a solenoid behave like a magnet? Can you determine the north and south poles of a current-carrying solenoid A solenoid is a long coil of circular loops of insulated copper wire. Magnetic field lines are produced around the solenoid when a current i... 1
- List three sources of magnetic fields. Three sources of magnetic fields are as follows: Current-carrying conductors Permanent magnets Electromagnets 1
- (a) An electric motor converts mechanical energy into electrical energy. (a) An electric motor converts mechanical energy into electrical energy. ► False An electric motor converts electrical energy into mechanica... 1
- At the time of short circuit, the current in the circuit (a) reduces substantially Correct option is c) increases heavily 2
- The essential difference between an AC generator and a DC generator is that (a) AC generator has an electromagnet Correct option d) AC generator has slip rings while the DC generator has a commutator. 1
- The device used for producing electric current is called a (a) generator (b) galvanometer (c) ammeter (d) motor Correct option is a) generator 2
- The phenomenon of electromagnetic induction is (a) the process of charging a body (c) producing induced current in a coil due to relative motion between a magnet and the coil 1
- Which of the following correctly describes the magnetic field near a long straight wire? (a) The field consists Correct option is d) The field consists of concentric circles centred on the wire 1
- What precaution should be taken to avoid the overloading of domestic electric circuits? The precautions that should be taken to avoid the overloading of domestic circuits are as follows: Too many appliances should not be connect... 1
- An electric oven of 2 kW is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. Current drawn by the electric oven can be obtained by the expression, P = VI Where, Current = I Power of the oven, P = 2 kW = 2000 W Voltage... 1
- Name two safety measures commonly used in electric circuits and appliances. Two safety measures commonly used in electric circuits and appliances are Electric Fuse: An electric fuse is connected in series it protects... 1
- A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes Correct option is c) half revolution 2
- Which sources produce alternating current? AC generators, power plants, etc., produce alternating current. 1
- Name some sources of direct current. Some sources of direct current are cell, DC generator, etc. 2