Electric Current and Its Effects
| Description: Electric Current and Its Effects | |
| Number of Questions: 18 | |
| Created by: Mohini Tyagi | |
| Tags: Science Class 7 Electricity Fundamentals of Electricity Electric Circuits |
An electric current flows from its source through a conducting material. Which of the following materials is a good conductor?
Which of the following is a bad conductor of electricity?
Which of the following is not a practical use of an electromagnet?
Which of the following statements is/are false? a. An electric current starts from the negative terminal of the cell and ends at the positive terminal. b. Electric current will flow only if all the elements in the circuit are in a firm electrical contact. c. In a battery with cells in series, the voltage increases but the current remains the same.
Which of the following is not a part of an electric bell?
Which of the following metals is used to make the resistance wire of a fuse?
Which of the following statements is/are false? a. The less the thickness of the connecting wire, the more is the current it can bear without getting hot. b. Filament based electric bulbs are inefficient and waste a large amount of electric energy. c. A fuse is the weakest part in an electric circuit.
Which of the following statements is/are false? a. A fuse, which is an alloy, is a short length of a wire with a very high melting point. b. In a battery with cells in parallel, the cells are connected in such a way that the positive terminals are connected to each other and the negative terminals are connected to each other. c. A fuse is always placed in the live wire of the electric circuit at a point where the current enters the circuit.
Match the following:
| a. Closed electric circuit | 1. The path along which the electric current flows. |
| b. Electric circuit | 2. The electric path, which starts from the positive terminal of a cell and ends at its negative terminal, without any break. |
| c. Open electric circuit | 3. The electric path, which starts from the positive terminal of a cell and is broken at some point. |
_________________ is used to measure potential difference between two known points in an electric circuit.
Which of the following instruments is used for detecting the flow of an electric current in a circuit?
Which of the following statements is/are false? a. The lesser the current flows through a coil, the more powerful is the electromagnet. b. Whenever current passes through a straight conductor, it behaves like a magnet. c. The magnetic field set up by the conductor is at right angles to the direction of the flow of current.
Which of the following automatically turns off when the current in a circuit exceeds the safe limit?
Which of the following metals is used to make the element of a heater?
Which of the following metals is used for making the filament of an electric bulb?
Which of the following statements is/are false? a. When a soft iron core is placed in a closed coil carrying current, it acts as an electromagnet. b. The magnitude of magnetic field decreases with the increase in the magnitude of current in the conductor. c. The amount of heat produced in a wire depends on its material, length and thickness.
Which of the following appliances is not having a heating element inside it?
Which of the following statements is/are false? a. Electric current on passing through the filament of the bulb produces no energy. b. The electric current is the drifting of a very large number of electrons through a conducting material. c. Electric energy changes into heat energy when passed through a conducting material, which offers some resistance.