Chemical Effects of Electric Current
Short Answer Type Questions
Question 1: Write a short note on LED.
Answer: It is the abbreviated form of Light Emitting Diode. An LED is enclosed in a glass housing; with two wires (called lead) coming out). One lead is slightly longer than another. An LED can glow even in the presence of weak current.
Question 2: Explain heating effect of electric current.
Answer: When electric current passes through a conductor, it increases the temperature of the conductor. This is called heating effect of electric current. Many electrical appliances work on heating effect of electric current, e.g. electric bulb, water heater, electric iron, etc.
Question 3: Explain magnetic effect of electric current.
Answer: When electric current passes through a conductor, a magnetic field is created around the conductor. This is called magnetic effect of electric current. This can be demonstrated by keeping a magnetic compass near a current-carrying conductor. A magnetic compass shows deflection when it is placed near a current carrying conductor. The devices which work on magnetic effect of electric current are: electric motor and electromagnet.
Question 4: What happens when electrodes are immersed in water and current is passed through them?
Answer: When electrodes are immersed in water and current was passed through water; bubbles of oxygen and hydrogen are produced. Oxygen bubbles are formed at the electrode connected to the positive terminal. Hydrogen bubbles are formed at the electrode connected to the negative terminal.
Question 5: We are advised not to touch electric switch with wet hands. Why?
Answer: Tap water conducts electricity because it contains various salts dissolved in it. Hence, it is advised not to touch an electric switch with wet hands. Touching electric switch with wet hands can result in electric shock.
Question 6: What is the drawback of electroplating?
Answer: Electroplating results in production of many harmful chemicals. Disposal of these chemicals is a big problem.
Long Answer Type Questions
Question 1: What is electrolysis? What are the signs of electrolysis?
Answer: When electric current is passed through a conducing solution, some chemical reaction takes place in the solution. This is called chemical effect of electric current, or electrolysis. Some of the signs of electrolysis are as follows:
- Bubbles of gas may be formed at electrodes.
- Deposits of metal may be seen on electrodes.
- Change of colour of solution may occur.
Question 2: Write the steps involved in electroplating.
Answer: Following steps are involved in electroplating:
- The material which needs to be coated with a layer is made the negative electrode (cathode).
- The plate of desired metal is made the positive electrode (anode).
- The conducting solution is made of a salt of desired metal.
- Electric current is passed through the solution.
- The desired metal dissociates from the plate (anode) and gets deposited on the material at negative electrode (cathode).
Question 3: Write some uses of electroplating.
Answer: Some uses of electroplating are as follows:
- Imitation jewelry is made by applying a layer of gold or silver.
- Applying a layer of chromium on an article by this method is called chrome plating. Parts of bicycle, motorbike and sanitary fittings are chrome plated by this method.
- Tin cans are made by electroplating tin on iron.
- Applying a layer of zinc on an article is called anodizing. Electric poles and beams on bridges are electroplated with zinc.
- Chrome plating and anodizing helps in preventing from corrosion.