NCERT Class 7 Science — Chapter 1: Electric current and its effects
Every question from this NCERT chapter, with a detailed explanation.
All Chapter 1: Electric current and its effects questions (25)
In the construction of an electromagnet, the wire wound around the soft iron core is typically:
To form a battery using two electrochemical cells, the correct connection sequence is:
Which of the following material properties is essential for a wire used as an electric fuse?
Why does an electric bulb fail to glow if the filament is broken, even when the switch is in the 'ON' position?
Match List I with List II and select the correct answer using the code given below: List I | List II A. Electric Fuse | 1. Magnetic effect of current B. Electric Bell | 2. Heating effect of current (Appliance) C. Electric Iron | 3. Source of electric current D. Electric Cell | 4. Safety device based on heating effect
The safety mechanism that utilizes the heating effect of electric current to break a circuit during a surge is the:
What is the immediate effect observed on a magnetic compass when it is brought near a wire carrying a direct current?
Consider the following statements about the heating element in electric appliances: 1. The element becomes red hot when connected to the electric supply. 2. The amount of heat produced is independent of the length of the wire used. 3. The heating element is typically a straight, thick copper rod. Which of the statements given above are correct?
Why are Compact Fluorescent Lamps (CFLs) and Light Emitting Diode (LED) bulbs preferred over incandescent electric bulbs? 1. Incandescent bulbs waste a significant part of electricity as heat. 2. CFLs and LEDs produce absolutely no heat during operation. 3. LED bulbs consume less electricity than incandescent bulbs for the same light intensity. Select the correct answer using the code given below:
Consider the following statements regarding the magnetic effect of electric current: 1. A current-carrying wire behaves like a magnet. 2. A compass needle placed near a current-carrying wire remains stationary. 3. The magnetic effect ceases when the current is switched off. Which of the statements given above are correct?
With reference to the magnetic effect of current, consider the following statements: 1. A current-carrying wire behaves like an electric insulator. 2. This effect is utilized to make electromagnets. 3. The effect was used to explain the working of the electric bell. Which of the statements given above are correct?
Why is the disposal of Compact Fluorescent Lamps (CFLs) considered more environmentally hazardous than that of traditional incandescent bulbs?
In electrical heating appliances such as irons and room heaters, the coiled wire responsible for heat generation is referred to as the:
Which of the following phenomena is responsible for the production of light in a traditional incandescent electric bulb?
Consider the following statements regarding the "filament" and the "element": 1. The filament is the component found in electric geysers. 2. The element is found in heating appliances like electric irons. 3. Both work on the principle of the heating effect of electric current. Which of the statements given above are correct?
Which of the following statements correctly describes the magnetic field generated by a straight current-carrying conductor?
The heating effect of current is utilized in which of the following? 1. Electric Generator 2. Electric Geyser 3. Electric Fuse 4. Electric Heater Select the correct answer using the code below:
Consider the following statements regarding the "filament" of a bulb: 1. The filament is a thick wire. 2. It glows when electric current passes through it. 3. If the filament breaks, the circuit remains closed. Which of the statements given above are correct?
What is the mechanism by which a fuse protects an electric circuit when the current exceeds the safe limit?
Which of the following components is primarily used in electric circuits to prevent damage from short circuits or overloading?
Consider the following statements regarding the "element" of an electric heater: 1. It is made of a material that has a high electrical resistance. 2. It absorbs heat from the surroundings when current flows through it. 3. It is typically coiled to increase the length of the wire in a small space. Which of the statements given above is/are correct?
The discovery that a current-carrying wire creates a magnetic field around it is attributed to:
With reference to the heating effect of electric current, consider the following statements: 1. A wire gets hot when an electric current passes through it. 2. The amount of heat produced depends solely on the magnitude of current, ignoring other factors. 3. The heat produced in a wire is independent of the material and thickness of the wire. Which of the statements given above is/are correct?
In the context of domestic electric circuits, the condition of "overloading" is typically caused by:
With reference to electrical safety, consider the following statements about the ISI mark: 1. The ISI mark is assigned by the World Health Organization. 2. The mark is an assurance of conformity to specifications. 3. It is mandatory for certain electrical appliances to ensure safety. Which of the statements given above are correct?