Hello Readers, Welcome to this new blog post in Class 7 Science. In my previous post I have provided you NCERT Solutions of this Chapter. Today, in this blog post I am providing you JKBOSE Solutions for Class 7 Science Chapter 14 Electric Current and its Effects. So, let us start by having an overview of what you studied in this chapter. Following topics are discussed in detail in this chapter:
- ELECTRIC CIRCUIT DIAGRAMS.
- HEATING EFFECT OF CURRENT.
- ELECTRIC FUSE.
- MAGNETIC EFFECT OF ELECTRIC CURRENT.
b. Uses of electromagnet.
- ELECTRIC BELL
1. ELECTRIC CIRCUIT DIAGRAMS: The standard method of drawing an electric circuit is termed as circuit diagram or electric circuit diagram. In circuit diagram, various electrical components of the circuit are represented by standard symbols. These electrical components are termed as elements of an electrical circuit.
2. HEATING EFFECT OF CURRENT: The production of heat in an electric device due to flow of electric current is called heating effect of electric current. The heating effect of current depends upon resistance of wire and magnitude of current flowing through it.
3. ELECTRIC FUSE: It is a safety device which works on the heating effect of electric current. It is used in electric circuits to prevent electric fires and damage to electric appliances due to massive flow of electric current. The electric fuse works on the principle of heating effect of current.
4. MAGNETIC EFFECT OF ELECTRIC CURRENT: When electric current passes through a wire, the current carrying wire behaves like a magnet. It is called as magnetic effect of electric current. This effect of electric current is used to many devices of our daily use like electromagnets, electric bells, electric fans, toys etc.
a. Electromagnet: The magnet made by using electric current is termed as electromagnet. It works on the basis of magnetic effect of electric current.
b. Uses of electromagnet: It used in making many devices like electric fan, electric bell, electric motor etc.
5. ELECTRIC BELL: An electric bell works on the magnetic effect of electric current. It has electromagnet in it.
That’s being said about basics of this chapter. Now let us move on to solutions section.
JKBOSE Solutions for Class 7 Science Chapter 14 Electric Current and its Effects
A. Fill in the blanks:
1. A drawing of an electrical circuit with standard symbols is called a circuit diagram.
2. Hot plates, electric toasters, and electric irons get hot when switched on because of the heating effect of current.
3. A fuse is a safety device.
4. A wire twisted in the form of a circle is called a coil.
5. An electromagnet consists of a soft iron core with an insulated wire wound around it.
B. Choose the correct answer:
1. A circuit diagram is
(a) a picture of a circuit
(b) a drawing of a circuit with standard pictures for the different electrical components.
(c) a diagram of an electrical circuit with standard symbols for the different electrical components.
(d) a difficult representation of an electrical circuit.
Ans. (c) a diagram of an electrical circuit with standard symbols for the different electrical components.
2. When an electric current pass through a wire, the wire gets hot. This is called
(a) Joule heating
(d) thermal heating
Ans. (a) Joule heating
3. An electric fuse is
(a) a safety device
(b) an appliance
(c) used to produce electric current
(d) use to heat a room
Ans. (a) a safety device
4. When we bring a magnetic compass near a current carrying wire,
(a) it deflects the magnetic needle of the compass
(b) it makes the magnetic needle point North
(c) it makes the magnetic needle point South
(d) it has no effect on the magnetic needle
Ans. (a) it deflects the magnetic needle of the compass
5. A coil refers to
(a) an electrical wire
(b) a fuse
(c) a current carrying conductor
(d) a wire twisted in the form of a circle
Ans. (d) a wire twisted in the form of a circle
6. An electromagnet act like a magnet
(a) when a current is passed through the coil
(b) all the time
(c) because it has a magnetic core
(d) only if a current does not pass through the coil.
Ans. (a) when a current is passed through the coil
7. In an electric bell, we have
(a) an electromagnet
(b) a hammer
(c) an interrupter
(d) all of these
Ans. (d) all of these
8. In an electric bell, which of these gets attracted to the electromagnet?
(a) the hammer
(b) the gong
(c) the soft iron strip
(d) the screw
Ans. (c) the soft iron strip
9. Which of these does not use heating effect of current?
(a) electric toaster
(b) electric fan
(c) electric Iron
(d) room heater
Ans. (b) electric fan
10. An electric fuse wire melts if the amount of current flowing through it.
(a) more than a minimum amount
(b) less than a minimum amount
(c) more than a maximum amount
(d) less than a maximum amount
Ans. (c) more than a maximum amount
C. Answer the following questions.
1. What is an electrical circuit?
Ans. The continuous conducting path between two terminals of cell or a battery along with electric current flowing through it is termed as electric circuit.
2. Draw an electrical circuit with an electrical cell, a bulb, and an ‘ON’ switch.
3. Why does an electric bulb get hot if it is kept ‘ON’ for a little while?
Ans. When electric bulb is kept ‘ON’ for a while, it becomes hot. It is due to heating effect of electric current.
4. Name three appliances that use the heating effect of electric current.
Ans. Following are the appliances that use the heating effect of electric current.
1) Electric toasters.
2) Electric ovens.
3) Electric hair dryers.
4) Hot plates.
5. What is an electric fuse?
Ans. It is a safety device which works on the heating effect of electric current. It is used in electric circuits to prevent electric fires and damage to electric appliances due to massive flow of electric current. The electric fuse works on the principle of heating effect of current.
6. Draw an electric fuse and explain briefly how it works.
An electric fuse works on the principle of heating effect of electric current. Greater the current flowing in the circuit, more heating is caused.
An electric fuse consists of thin wire placed inside a glass or ceramic cartridge. The wire in electric fuse is made up of material which melts on heating. It is designed in such a way that certain maximum amount of current is allowed to flow through it. If amount of current flowing in the circuit exceeds the maximum limit, the wire in the fuse melts away due to heating. As a result, circuit breaks and flow of current is stopped. It prevents electrical fires in case of short circuit or excessive flow of current in the circuit.
7. How can you show that an electric current has a magnetic effect?
Ans. We can show that electric current has a magnetic effect by performing following activity:
Take the cardboard tray from inside a discarded matchbox. Wrap an electric wire a few times around the cardboard tray. Place a small compass needle inside it. Now connect the free ends of this wire to an electric cell through a switch as shown in figure.
8. What is an electromagnet?
Ans. When an electric current is passed through a core (A piece of soft iron around which wire is wrapped), it behaves like a magnet. A magnet made by such arrangement is known as electromagnet.
9. Name two factors on which the strength of an electromagnet depends.
Ans. The strength of an electromagnet depends upon following factors:
(i) Number of turns wound around the core.
(ii) Amount of current passing through it.
10. Explain the working of an electric bell using diagrams.
Ans. Working of an electrical bell.
There are three steps in the working of an electrical bell. These are as under:
Step 1. When you push the switch of the bell, the electric current flows to the electromagnet.
Step 2. The electromagnet attracts the soft iron strip. The hammer attached to the strip then hits the gong, causing a ring.
Step 3. When the soft iron strip gets attracted to the electromagnet, it no longer touches the screw (interrupter) and hence the circuit is broken, (much like a switch being turned off). This turns off the electromagnet and it can no longer attract the soft iron strip. The soft iron strip returns to its initial position, touching the screw (interrupter). This results in the circuit being complete and current flows again.
Steps 1 to 3 repeat in quick succession as long as the switch is on.
This is how we hear a continuous ring of the bell.
That’s it for JKBOSE Solutions for Class 7 Science Chapter 14 Electric Currents and its Effects. Hope this post has helped. Share you views in comments.Here is Complete Solution of Class 7 Science Textbook (NCERT/JKBOSE).
- Chapter 1: Nutrition in Plants.
- Chapter 2: Nutrition in Animals.
- Chapter 3: Fibre to Fabric.
- Chapter 4: Heat.
- Chapter 5: Acids, Bases and Salts.(NCERT)
- Chapter 5: Acids, Bases and Salts. (JKBOSE)
- Chapter 6: Physical and Chemical Changes.
- Chapter 7: Weather, Climate and Adaptations of Animals to Climate.
- Chapter 8: Winds, Storms and Cyclones.
- Chapter 9: Soil.
- Chapter 10: Respiration in Organisms.
- Chapter 11: Transportation in Animals and Plants.(NCERT)
- Chapter 11: Transportation in Plants and Animals. (JKBOSE)
- Chapter 12: Reproduction in Plants.(NCERT)
- Chapter 12: Reproduction in Plants (JKBOSE)
- Chapter 13: Motion and Time.
- Chapter 14: Electric Currents and Circuits.
- Chapter 15: Light.
- Chapter 16: Water.
- Chapter 17: Forests: Our Lifeline.
- Chapter 18: Waste Water Story.