NCERT solution for class 7 || Science || Chapter 14 -Electric current and its effect


 NCERT solution . > Class 7 >Science 
NCERT solution for class 7 || Science || Chapter 14 -Electric current and its effect 

Chapter 14 -Electric current and its effect

Exercise

 Q1. Draw in your notebook the symbols to represent the following components of electric circuits : connecting wires switch in the off position sell switch in the on position and battery 

Answer - 


Q2. Draw the circuit diagram to represent the circuit shown in figure 14 . 21.


Answer -  In the above diagram the safety pin is not attached to the holding pin so the circuit is incomplete .It acts as a switch when we attached to the sefty pin to the holding pin then circuit is complete and the bulb become glow 


Q3. Figure 14 .22 show found four cells fixed on a board draw lines to indicate how you will connect their terminals with wires to make a battery of four cells?  


Answer - 



Q4. A bulb in a circuit shown in a figure 14 . 23 does not glow can you identify the problem make necessary changes in the circuit to make the bulb glow 

Answer -   Because in battery both the positive terminals are join to each other but it is not possible When two similar terminals are attached to each other electricity will not be flow from it . If we turn the position of any one  cell of them then the bulb becomes glow 

Q 5. Name any two effect of electric current ? 

Answer - Two effect of electric current are 

  • Heating effect of electric current 
  • eg. Electric iron electric heater etc.
  • Magnetic effect of electric current 
  • Eg. Electric bell electromagnet electric toy etc 

Q6. When the current is switched on through a wire a compass needle kept nearby get deflected from its North and South position explain? 

Answer - When current is passing through the wire then it shows the magnetic behaviour when the  compass needle get nearby it then due to magnetic effect of electric current it change its position north to south

Q7. Will the compass needle shows deflection when the switch in the circuit shown in figure

 14 .24 is closed .  

Answer - Circuit shown in figure 14.24 is not complete so the wire does not act as a magnet and there is no fluctuation of compass needle if we placed it in contact with wire

Q8. Fill in the blanks 

a) Longer lines in the symbol for a cell represent its positive terminal .

b) The combinations of two or more cells is called a battery.

c) When current is switched on in a room heater is it produces heat

d) The safety device based on the heating effect of electric current is called from fuse.

Q9. Mark T if the statement is true and F if it is false 

a) To make a date tree of two cells the negative terminal of once a is connected to the negative terminal of other cell. 

b) When electric current through the fuse exceeds a certain limit the fuse wire melts and breaks 

c) An electromagnet does not attract a piece of iron .

d) An electric bell has an electromagnet .

Answer -  a) false 

b) true 

c) false 

d) true 

Q10. Do you think an electromagnet can be used for separating plastic bags from a garbage heap explain ? 

Answer - Electromagnets are only attract the magnetic material like iron, Cobalt and nickel but plastic bags are non magnetic materials therefore electromagnet cannot be used for separating the plastic bags from the garbage off heap

Q11. An electrician is carrying out some repairs in your house we want to replace a fuse by a piece of wire would you agree give reason for your  response?  

Answer - No the electrician not replace the used by the piece of wire because the wire used in fuse has low melting point so it can prevent the electronic gadgets by high current . And many of the wires have high melting point so it could not prevent the extra electric current. 

Q12. Zubeda made an electric circuit using a cell holder shown in figure 14.4 a switch and a bulb when she put the switch in the on position the bulb did not glow help the weather in identifying the possible defect in the circuit ? 

Answer-  There are two conditions whether we are identifying the possible defect of the circuit 

1. Two opposite terminals are attached to each other then the current will be pass 

2. The rubber of the  cell holder are properly tight so the two terminals are properly contact with each other and completed the circuit

Q13. In the circuit shown in figure 14. 25   

i) Would any of the bulb glow when the switch is in the off position. 

ii) What will be the other in which the bulbs A, B and C will glow when the switch is moved to the on position . 

Answer- 1. Know if the switch is in off position then current will not be flow from the circuit 

2. When the the switch is in on position then all the bulbs are glow at a time because all they are attached with same battery and same switch


Comments

Post a Comment

Text

Popular posts from this blog

NCERT solution for class 6 || Science || Chapter 13 - Fun with magnets

  NCERT solution > class 6 > Science  Chapter 13 - Fun with magnets  Exercise  Q1. Fill in the blanks in the following.  i) Artificial magnet are made in different shapes such as  H orse shoe and cylindrical ii) The materials which are attracted towards a magnet are called Magnetic materials  iii) Paper is not Magnetic material . iv) In olden days sailor used to find direction by suspending a piece of Magnet   v) A magnet always has Two poles.  Q2. State whether the following statements are true or false  i) Cylindical magnet has only one pole  ii) Artificial magnets were discovered in Greece . iii) Similar poles of a magnet repel each other . iv) Maximum iron filings stick in the middle of the bar magnet when it is brought them near.  v) Bar magnets always point towards north south direction. vi) Compass can be used to find east west direction at any place . vii) Rubber is a magnetic material . Answer - i) fals...
Read more

NCERT Solution //class 8// Science // Chapter 8- Cell structure and functions

Image
NCERT solutions of class 8 >Science > Chapter 8 - Cell structure and functions  NCERT Solution //class 8// Science // Chapter 8-  Cell structure and functions 1 .   Indicate whether the following statements are true or false a)  Unicellular organisms have one -celled body.     Answer. - True b) Muscle cells are branched Answer. -True c) The basic living unit of an organism is an organ Answe r-. False d) Amoeba has irregular shape Answer . True   2. Make a sketch of human nerve cell what function do nerve cell perform?  Answer .        Function of nerve cells-  Nerve cell carry the signal of sensation from different body parts to brain or  it again carry the reverse signal from brain to other body parts. 3. Write a short notes on following  a) Cytoplasm -             The space present between the nuclear membrane and plasma membrane is filled with the translucent ...
Read more

NCERT solution for class 6 || science || chapter 14 - Water

 NCERT solutions>  Class 6 > Science  NCERT solution for class 6 || science || chapter 14 -  Water Chapter 14 -Water   Exercise  Q1. Fill up  the blanks in the following  a) The process of changing of water into its vapour is called evaporation b) The process of changing water vapour into water is called condensation  c) No rainfall for a year or more may lead to drought in that region . d) Excessive rain may cause floods . Q2. State for each of the following whether it is  due to evaporation or condensation  . a) Water drops appear on the outer surface of  a glass containing cold water. b) Steam rising from wet clothes while they are iron  c) Fog appearing on a cold winter morning  d) Blackboard dries up after wiping it  e) Steam rising from ala hot girdle when water is sprinkled on it . Answer -  a) Condensation  b) Evaporation  c) Condensation  d) Evaporation  e) Evaporati...
Read more