Topics
Crop Production and Management
- Crop and Its Types
- Soil Formation and Preparation for Agriculture
- Agricultural Implements
- Manuring (Biomanuring)
- Fertilizers
- Methods to Replenish Nutrients in Your Soil
- Improved methods of agriculture
- Food Security
- Weeding
- Harvesting of Crops
- Storage of Food Grains
- Animal Products used as Food
Microorganisms: Friend and Foe
Synthetic Fibres and Plastics
- Fibre
- Fabrics
- Man-made Fibre: Synthetic Fibres
- Rayon
- Nylon
- Dacron, Terylene, Terene
- Man-made Fibre: Plastics
- Biodegradable Plastics
- Harmful Effects of Plastics
- Recycling of Plastic
Coal and Petroleum
- Energy Resources > Conventional energy resources or non-renewable energy resources
- Carbon: A Versatile Element
- Special Features of Carbon
- Non-crystalline/Amorphous Forms: Coal
- Extraction of Coal
- Non-crystalline/Amorphous Forms: Coke
- Petroleum
- Refining of Crude Petroleum
- Conventional Sources of Energy > Natural Gas
- Some Natural Resources Are Limited
Materials: Metals and Non-metals
Combustion and Flame
- Chemical Properties of Carbon Compounds > Combustion
- Precautions and Safety Measures
- Types of Combustion
- Flame
- Fuel
- Types of Fuel
- Fuel Efficiency
Conservation of Plants and Animals
- Deforestation and Its Causes
- Consequences of Deforestation
- Conservation of Forests
- Conservation of Wildlife
- Endemic Species
- Migration
- Recycling of Paper
- Reforestation
Reproduction in Animal
- Fertilization in Human
- Embryo Formation in Viviparous and Oviparous Animals - Young Ones to Adults
Reaching the Age of Adolescence
- Secondary Sex Characteristics
- Role of Hormones in Initiating Reproductive Function
- Reproductive Phase of Life in Humans
- Hormones Other than Sex Hormones
- Role of Hormones in Completing the Life History of Insects and Frogs
- Nutritional Needs of Adolescents
- Personal Hygiene for Adolescence
Cell - Structure and Functions
Force and Pressure
- Force
- Force - Push or Pull
- Forces Are Due to an Interaction
- Exploring Forces
- A Force Can Change the State of Motion
- Force Can Change the Shape of an Object
- Effect of Force
- Types of Forces>Contact and Non-Contact Forces
- Thrust and Pressure
- Pressure of liquid
- Factors Affecting Liquid Pressure
- Atmospheric Pressure
Friction
- Force of Friction
- Factors Affecting Friction
- Friction - A Necessary Evil
- Effects of Friction
- Increasing and Reducing Friction
- Fluid Friction
Sound
Chemical Effects of Electric Current
- Conductor of Electricity: Liquid
- Electricity
- Chemical Effects of Electric Current
- Electrical Conduction in Solids
Some Natural Phenomena
- Lightning and Lightning Safety
- Force of Friction
- Electric Charge
- Types of Charges and Their Interaction
- Transfer of Charges
- Electroscope
- Lightning and Lightning Safety
- Earthquake
- Protection Against Earthquakes
Light
- Climatic Factors > Light
- Reflection of Light
- Terms Used in Reflection of Light
- Law of Reflection of Light
- Types of Reflection
- Multiple Reflections
- Prism
- Dispersion of Light
- The Human Eye
- Care of the Eyes
- Visual Impairment and Braille System
Star and Solar System
Pollution of Air and Water
- Pollution
- Case Study: The Taj Mahal
- Green House Effect
- Preventive Measures of Green House Effect
- Preventive Measures of Global Warming
- Case Study: Ganga Pollution and Ganga Action Plan
- Potable Water
- Purification of Water
Maharashtra State Board: Class 7
Gold Leaf Electroscope:
A gold leaf electroscope is a simple tool used to detect electric charges on objects.
1. Parts of the Electroscope
- Copper rod: A rod with a metal disc on top.
- Gold leaves: Two thin gold leaves connected to the bottom of the rod.
- Glass bottle: The rod with gold leaves is placed inside the bottle to protect the leaves.
2. Working
- When an uncharged object is brought near the metal disc, the gold leaves stay closed because no charge is transferred.
- When a charged object (like a rubbed rod) is brought near the metal disc, the same type of charge spreads to both gold leaves. Since both leaves now have the same charge, they repel each other and move apart (open up).
- Discharging the electroscope: If you touch the metal disc with your hand, the charge flows through your body into the earth. The gold leaves collapse (come back together) because they lose their charge.
3. Conclusion: The gold leaf electroscope shows whether an object is charged or not by checking if the leaves stay closed or move apart.
