A response is a reaction to a question, experience, or some other type of stimulus like heat, light, etc. Adaptation refers to the changes in the physical and behavioural characteristics of an organism that help them to survive in the changing environment.

A magnetic compass is a simple device used for finding direction. It consists of a magnetic needle that can turn freely about its centre. The needle is encased in a box with a transparent top. Directions are either printed on a card placed below the needle or marked on top of the box. Usually, the north pole of the needle is painted red or blue, or is in the shape of an arrowhead. When kept away from magnetic materials, the north pole of the needle points towards the geographical north. To find directions, the box is turned till the north mark on the card falls exactly below the north pole of the needle. In this position, the other directions are also indicated by the card.

Handle of screwdriver used by electrician is made up of plastic because plastic is an insulater, so he will not get a shock while repairing switch.

According to Greek legend magnetism was first discovered by a shepherd named Megnes, who lived in Megnesia, Greece. Megnes was herding his sheep through the mountains. Suddenly he noticed the ferrule of his stick and nails in his sandals got stuck to a rock. The iron in his stick and nails had become attracted to the magnetic rock. The stone was named as magnetite, after the name of the shepherd or the country it was found in. It was also known as loadstone because of its attractive properties.

Below are a certain conditions where a magnet may get damaged:

• Magnets lose magnetism when they are heated, hammered or dropped from some height.
• Magnets become weak if they are not stored properly.

Magnets should be stored as mentioned below:

• Magnets should be kept in pairs with their unlike poles on the same side. They must be separated by a piece of wood while two pieces of soft iron should be placed across their ends.
• For horse-shoe magnet, one should keep a piece of iron across the poles.

Holiday homework

Wilhelm Roentgen, a German professor of physics, was the first person to discover electromagnetic radiation in a wavelength range commonly known as X-rays today.

X-rays are a form of electromagnetic radiations which emitted when matter is bombarded with fast electrons.

Wilhelm Conrad Roentgen.

Mucus is a slippery secretion produced by mucous membranes. Mucous fluid is typically produced from cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which contain both serous and mucous cells. It is a viscous colloid containing antiseptic enzymes,immunoglobulins, inorganic salts, proteins such as lactoferrin, and glycoproteins known as mucins that are produced by globlet cells in the mucous membranes and submucosal glands. This mucus serves to protect epithelial cell in the respiratory, gastrointestinal, urinogenital, visual and auditory systems in mammals. A major function of this mucus is to protect against infectious agents such as fungi, bacteria and viruses. The average human body produces about a litre of mucus per day.  

The work of a switch is to allow or not allow the current pass through the circuit

A switch is a simple device that either breaks the circuit or completes it.
When switch is in ‘OFF’ position, then the circuit is open i.e. no current flows through the circuit and when switch is in ‘ON’ position, then the circuit is complete i.e. current flows through the circuit.

i. Rectilinear motion: This type of motion is a straight line motion. Rectilinear motion takes place in a fixed direction. Examples of rectilinear motion: a. The movement of a bullet fired from a gun. b. The march-past of soldiers in a parade. ii. Circular motion: A path having the shape of a circle is called circular path. When an object moves along a circular path, it is called circular motion. Examples of circular motion: a. The movement of moon around the earth. b. Movement of artificial satellites around the earth. iii. Periodic motion: Periodic motion is the motion which repeats itself after regular intervals of time. Examples of periodic motion: a. The motion of seconds’ hand of a watch. b. The revolution of earth around the sun. iv. Rotational motion: When an object turns or spins about a fixed axis, it is called rotational motion. Examples of rotational motion: i. The motion of a spinning top. ii. The spinning of earth on its axis.

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The living organisms are known as biotic components

The Organisms, both plants and animals are called biotic factors. . Hope you get help

Electricity is needed to run a radio

b) Electricity

Electricity

We will rub magnet on the iron strip 60 or more times to make the iron strip magnetic

Define of PERIODIC MOTION

We can use paper bag instead of plastic

The process of becoming accustomed to a different environment over short periods is called acclimatisation. Excretion is defined as the process of removing or discharging metabolic waste matter from an organism .

Transparent objects are those objects through which rays of light can pass easily

For example - Water  and glass is the basic example of a transparent objects

Translucent  objects are those objects through which only few rays of light can pass through it.

For example- A paper

Opaque objects are those objects where no lays of light can pass through them.

For example- wood

When light falls on an opaque object, a dark patch is formed on the other side of the object; if a screen is present on the other side. Three things are required for formation of shadow, viz. a source of light, an object and a screen.

The size of shadow depends on the distance of source of light and on the angle at which the light rays fall on the object.

If the source of light is closer to the object, a larger shadow is formed than when the source of light is far from the object.

If the angle of incident light is smaller, the shadow is longer. On the other hand, if the angle of incident light is bigger, the shadow is smaller. This explains, why our shadows are longer in the morning and evening and smaller in the noon.

When the snail has to move the foot comes out of the shell through an opening in the shell. It produces mucus ,so the animals gets a smooth surface to crawl. The muscular foot produces a series of wave like movement that helps the animals to move forward.

• Snails commonly found on land or in soil.
• Snail possesses wavy movement with muscular contraction.
• It also secrets sticky substance called mucus which helps to reduce grip between the snail and the ground so that they can move easily.
• It has shell on its back which is hard but not made of bone and is not helpful in locomotion.
• Snail locomotion is frequently called crawling.

The direction of electric current in an electric circuit is from the positive terminal to the negative terminal. This is opposite to the direction of flow of electrons; which is from the negative terminal to the positive terminal.

When light falls on an opaque object, a dark patch is formed on the other side of the object; if a screen is present on the other side. Three things are required for formation of shadow, viz. a source of light, an object and a screen.

The size of shadow depends on the distance of source of light and on the angle at which the light rays fall on the object.

If the source of light is closer to the object, a larger shadow is formed than when the source of light is far from the object.

Light travels in straight lines. The formation of shadow by a source of light suggests that light travels in straight lines. The shape of the shadow remains the same as the shape of the object because light travels in straight line path. The property of light travelling in straight lines is called rectilinear propagation of light.

Outstanding ???

Because it cannot dissolves in water and it can harm the aquatic plants and animals

Light travels in straight lines. The formation of shadow by a source of light suggests that light travels in straight lines. The shape of the shadow remains the same as the shape of the object because light travels in straight line path. The property of light travelling in straight lines is called rectilinear propagation of light.

• The most extensive use of gold plating is on jewellery and watch cases.
• Zinc coatings prevent the corrosion of steel articles.
• Nickel and chromium-coated articles are used in automobiles and household appliances.

They have certain features that help them live in the surrounding they are normally found the presence of specific features or certain habits is called afaptation

Adaptation is a method byorganisms get well to a habitats

adaptation is the method by organisms get well adjusted to the climate like the lives of cactus plant is eithere absent or very small to reduce the loss of water from the lives through transpiration

Adaptation: The presence of some specific features and certain habits which allow an organism to live in its habitat is called adaptation. Organisms show adaptation according to their habitat.

The presence of specific features of a plant or an animal living in a particular habitat is called adaptation

The cyclic movement of water from the atmosphere to the earth and back to the atmosphere through various processes is called as water cycle different steps of water cycle include evaporation and transpiration condensation precipitation and surface runoff evaporation the water present on the surface of ocean separates by the sunset this process of conversion of water from liquid to Vapour state is called evaporation .

The cyclic movement of water from the atmosphere to the Earth and back to the atmosphere through various processes is called as water cycle.
Different steps of water cycle include evaporation, transpiration, condensation, precipitation and surface run-off.

a) Evaporation - The water present on the surface of oceans evaporates by the sun’s heat. This process of conversion of water from liquid state to vapour state is called evaporation. Evaporation also takes place from wet clothes, fields, ponds, lakes and rivers.

b)Transpiration - Plants take in water from the soil to prepare their own food and also for other life processes. They release excess water into air in the form of water vapour by the process of transpiration.

c) Condensation - The evaporated water is carried away by warm air. As the warm air moves higher from the surface of the Earth, it starts to cool down. This water vapour condenses to form tiny water droplets which float in air to form clouds or fog.

d) Precipitation - All these droplets collect to form bigger drops of water. Bigger water drops come down ads rain by the process of precipitation. If the air is too cold, the water drops can become snow or hail and may settle on the top of a mountain. When these snow or hail melts, they can become part of a river or a stream.

e) Surface run-off – Some amount of rain water is absorbed by the soil and settles down as ground water. Most of the rain water flows down the hills and mountains to collect into rivers, lakes or streams. Rain also washes away the topmost layer of the soil into water bodies.

This circulation of water through all these different factors is called as water cycle.

What is non biodegradable

A Non-Biodegradable material can be defined as a kind of substance which cannot be broken down by natural organisms and acts as a source of pollution.