Fill in the blanks with suitable words.
(a) Time taken by an object to complete one oscillation is called ................... .
(b) Loudness is determined by the .........................of vibration.
(c) The unit of frequency is..........................
(d) Unwanted sound is called ......................... .
(e) Shrillness of a sound is determined by the ................. of vibration.
(a) Time period
Time period may be defined as the time taken by an object or a body to complete the one oscillation or a cycle.
(b) Amplitude
Amplitude shows the loudness of the sound. When the amplitude of the vibration is larger, then the sound produced will be very loud. When the amplitude is small then the produced sound will be feeble.
(c) Hz
Hertz is the unit of frequency. Frequency may be defined as the number of oscillation in one second.
(d) Noise
The sound which is unpleasant and unwanted to ears known as noise whereas the sound which us pleasant to the ears is known as music.
(e) Pitch
If the frequency of the vibration is higher, then the produced sound will be shrill and it has high pitch whereas if the frequency of vibration is lower, then the sound will contain lower pitch.
Sketch larynx and explain its function in your own words.
Explain in what way noise pollution is harmful to humans.
List sources of noise pollution in your surroundings.
Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.
Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. Can you explain?
Which of the following voices is likely to have minimum frequency?
(a) Baby girl (b) Baby boy
(c) A man (d) A woman
Identify the part which vibrates to produce sound in the following instruments:
(a) Dholak (b) Sitar (c) Flute
A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
What is the difference between noise and music? Can music become noise sometimes?
Choose the correct answer :
Sound can travel through
(a) gases only (b) solids only
(c) liquids only (d) solids, liquids and gases.
Which of the following can be beaten into thin sheets?
(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen
Fill in the blanks
(a) Most liquids that conduct electricity are solutions of , ______________ and ______________.
(b) The passage of an electric current through a solution causes ______________ effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the terminal of the battery.
(d) The process of depositing a layer ofany desired metal on another material by means of electricity is called .
Give two examples each of situations in which you push or pull to change the state of motion of objects.
Fill in the blanks:
(a) Friction opposes the _____________ between the surfaces in contact with each other.
(b) Friction depends on the _____________ of surfaces. (c) Friction produces __________.
(d) Sprinkling of powder on the carrom board ________ friction.
(e) Sliding friction is ___________ than the static friction.
List conditions under which combustion can take place.
Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have one-celled body. (T/F)
(b) Muscle cells are branched. (T/F)
(c) The basic living unit of an organism is an organ. (T/F)
(d) Amoeba has irregular shape. (T/F)
Which of the following cannot be charged easily by friction?
(a) A plastic scale
(b) A copper rod
(c) An inflated balloon
(d) A woollen cloth.
Fill in the blanks:
(a) A place where animals are protected in their natural habitat is called .
(b) Species found only in a particular area is known as .
(c) Migratory birds fly to far away places because of changes.
Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room. Explain.
What are the different ways in which water gets contaminated ?
State the laws of reflection.
Draw a labeled sketch of the human eye.
Write notes on—
(a) Adam’s apple.
(b) Secondary sexual characters.
(c) Sex determination in the unborn baby.
Differentiate between the following:
(a) Wildlife sanctuary and biosphere reserve
(b) Zoo and wildlife sanctuary
(c) Endangered and extinct species
(d) Flora and fauna
The radius of Jupiter is 11 times the radius of the Earth. Calculate the ratio of the volumes of Jupiter and the Earth. How many Earths can Jupiter accomodate?
How is an embryo developed?
Write 10 lines on the usefulness of microorganisms in our lives.
What is a constellation? Name any two constellations.
Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise Rana, giving your reason.
In the following Table some substances are given in Column I. In Column II some uses are given. Match the items in column I with those in Column II.
Column I | Column II |
---|---|
(i) Gold (ii) Iron (iii) Aluminium (iv) Carbon (v) Copper (vi) Mercury |
(a) Thermometers (b) Electric Wire (c) Wrapping food (d) Jewellery (e) Machinary (d) Fuel |