Maharashtra Board Class 8 Science Solution Chapter 4 – Current Electricity and Magnetism
Balbharati Maharashtra Board Class 8 Science Solution Chapter 4: Current Electricity and Magnetism. Marathi or English Medium Students of Class 8 get here Current Electricity and Magnetism full Exercise Solution.
Std | Maharashtra Class 8 |
Subject | General Science Solution |
Chapter | Current Electricity and Magnetism |
Exercise Solution
(1) Write proper words from the following group of words in the blanks.
(magnetism, 4.5V, 3.0V, gravitational attraction, potential difference, potential, higher, lower, 0V)
(a.) Water in the waterfall flows from a higher level to the lower level because of ________
Ans. gravitational attraction
(b) In an electric circuit, electrons flow from a point of _____ potential to the point of _____ potential.
Ans. higher, lower.
(c) The difference between the electrostatic potential of the positive end the negative end of an electric cell is the ______ of the cell.
Ans. potential difference.
(d.) Three electric cells of potential difference 1.5 V each have been connected as a battery. The potential difference of the battery will be ______ V.
Ans. 4.5 V.
(e.) An electric current flowing in a wire creates ______ around the wire.
Ans. Magnetism.
(2.) A battery is to be formed by joining 3 dry cells them with connecting wires. Show how will you connect the wires by drawing a diagram.
Solution: Here, 3 dry cell are seen to be connected in series. The purpose of doing this is to obtain more potential difference than that of a single cell. Therefore, it is possible to obtain higher current.
(3) In an electric circuit, a battery and a bulb have been connected and the battery consists of two cells of equal potential difference. If the bulb is not glowing, then which tests will you perform in order to find out the reason for the bulb not glowing?
Solution: If bulb is not glowing than the requiring test are following-
(i) To check if the cells are connected in the correct orientation.
(ii) Check for loose connection then check the bulb.
(iii) Series would be – + – + so the voltage is additive. With a ++ or — connection, result that voltage will be zero.
(iv) Using Voltmeter.
(4) Electric cells having 2V potential difference each have been connected in the form of a battery. What will be the total potential difference of the battery in both cases?
Ans.
(5.) Describe the construction, working and usefulness of a dry Cell, with the help of a diagram.
Ans. Dry Cell:
Construction & Working:-
Take a lead dry cell & remove its outer coating. Inside you will find a whitish, metal layer. This is the Zinc (Zn) metal layer. This is the negative terminal of the cell. Now, carefully break open this layer. There is another layer inside. An electrolyte is filled between these two layers. The electrolyte contains negatively charged & positively charged ions. There are carries electricity. The electrolyte is a wet pulp of Zinc Chloride (ZnCl2) & Ammonium Chloride (NH4Cl). There is a graphite rod at the centre of the cell. A paste of Manganese di Oxide (MNO2) is filled outside the rod. Because electric charge is produced on the two terminals & an electric current flows in the circuit.
Usefulness of dry cell:-
(i) The dry cell uses a paste electrolyte, with only cough moisture to allow current flow.
(ii) It would be used without concern. With their orientation, or risk of spoilage.
(6.) Describe the construction and working of an electric bell with the help of a diagram.
Ans. Electric Bell:-
Construction:-
A simple electric cell is made up of an electrolyte & two electrodes. The electrolyte is a conductive solution containing negative ions which moves toward anode & positive ions which moves towards the cathode.
Working:-
Electric bell works on the principle of electromagnet. The switch is pressed & current flows through the circuit. The electromagnet is powered & generates a magnetic filled.