Electricity Circuits and Their Components — Question 17

The LED bulb will glow when the longer wire i.e., the positive terminal of LED is connected with positive terminal of battery and shorter wire i.e., the negative terminal of LED is connected with negative terminal of battery.
According to the given connection the LED will not glow, as negative terminal of LED is connected with positive terminal of battery. The correct connection will be:
Class 7 Electricity Circuits and Their Components Question Answer (Activities)
Activity 3.1: Let Us Explore (Page 24)
Observation and conclusion: The torchlight glows when the switch is turned on because the electric cells inside provide energy to the lamp. When the switch is off, the circuit breaks and the lamp does not glow. This shows that a complete circuit is needed for electricity to flow.
Activity 3.2: Let Us Observe (Page 25)
Conclusion: An electric cell has two terminals  a positive terminal (metal cap) and a negative terminal (metal disc). These terminals help in the flow of electric current. The electric cell acts as a portable source of electrical energy.
Activity 3.3: Let Us Experiment (Page 25)
Observation and conclusion: The torchlight glows only when the cells are placed in the correct order, with the positive terminal of one cell connected to the negative terminal of the next. This correct arrangement forms a battery, which allows electricity to flow and light the lamp.
Activity 3.4: Let Us Observe (Page 26)
Observation and conclusion: The glowing part of an incandescent lamp is a thin wire called the filament. The filament gets hot and glows when electricity passes through it, producing light. It is connected to two thicker wires that act as terminals. These wires are fixed in a way that they do not touch each other inside the lamp.
Activity 3.5: Let Us Observe (Page 27)
Observation and conclusion: LEDs do not have filaments like incandescent lamps. They have two terminals one positive (longer wire) and one negative (shorter wire). The LED lights up when connected correctly to a battery. Some torch lamps may use LEDs of different shapes and colours.
Fig. 3.7 (a) An electric cell holder with two wires attached (b) An electric cell inside the cell holder (c) Wires connected to an electric cell using electrical tape
Fig. 3.8 (a) An electric lamp holder with wires attached (b) An incandescent lamp inside the lamp holder (c) Wires connected to incandescent torch lamp with electrical tape
Table 3.1: Trying to Make the Lamp Glow
Observation and conclusion: The electric lamp will glow only when the current will flow inside the circuit. When all the connections are properly connected then only current will flow and the lamp will glow otherwise the current will not flow in the circuit and the lamp will not glow.
Activity 3.7 Let Us Experiment (Pages 30-31)
Observation and conclusion: The LED glows only when it is connected correctly the longer wire to the positive terminal and the shorter wire to the negative terminal of the battery as shown in fig.(a). This shows that electric current flows in only one direction through an LED. If the connections are reversed, the LED does not glow. This helps us learn how to properly connect components in a circuit.
Activity 3.8 Let us Test (Page 32)
Observation and conclusion: We constructed a simple switch using a safety pin and drawing pins on a cardboard piece. When connected with wires, this setup works as a basic switch that can open or close a circuit.
Activity 3.9 Let Us Test (Page 32)
Observation and conclusion: By connecting the switch to a battery and lamp, we saw that the lamp glows only when the safety by opening or closing the path.
Activity 3.10 Let Us Draw (page 34)
Observation and conclusion: The circuit diagram can be drawn easily with the help of symbols of different electric components.
Activity 3.11 Let Us Identify (Page 35)
Table 3.3: Identifying Conductors and Insulators
Object
Material: It is made up of
Lamp glows (Yes/No)
Conclusion (Conductor/ Insulator)
Stick
Wood
No
Insulator
Scale
Plastic
No
Insulator
Bangle
Glass
No
Insulator
Paper strip
Paper
No
Insulator
Candle
Wax
No
Insulator
Key
Metal
Yes
Conductor
Eraser
Rubber
No
Insulator
Paperclip
Metal
Yes
Conductor
Copper wire
Copper
Yes
Conductor
Aluminum foil
Aluminum
Yes
Conductor
Rubber band
Rubber
No
Insulator
Glass jar
Glass
No
Insulator
Observation and conclusion: This activity shows the difference between conductors and insulators. Conductors allow electricity to flow through them, making the lamp glow. Insulators, on the other hand, do not allow the current to pass through them, so the lamp stays off.