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Science · 2026 · 5 marks
CBSE 2026 · Region 3 · Set 3 · Q39
Attempt either (a) or (b) :A person was repairing an electric heater. He observed that there were three different connecting wires of three different colours in the cable attached to the heater.(i)What are these three different wires called ? Name them colourwise.(ii)What is the value of standard potential difference at which electricity is supplied in Indian homes for lighting ?(iii)What is the role of (I) earthing and (II) fuse in domestic electric circuits ?(b)Write the name and statement of the rule used to determine the direction of the :(I)force experienced by a straight current-carrying conductor placed in a uniform magnetic field perpendicular to the field.(II)magnetic field produced around a straight conductor carrying electric current.(ii)Two straight current-carrying conductors (A) and (B) are shown in the figures below :
(A)(B)(I)Mark the direction of the magnetic fields around these current-carrying conductors (A) and (B).(II)Compare the strengths of magnetic fields produced(1)at points P and Q and ($\displaystyle 2$) at points Q and R due to these current-carrying conductors, qualitatively.
Attempt either (a) or (b) :
A person was repairing an electric heater. He observed that there were three different connecting wires of three different colours in the cable attached to the heater.
(i)
What are these three different wires called ? Name them colourwise.
(ii)
What is the value of standard potential difference at which electricity is supplied in Indian homes for lighting ?
(iii)
What is the role of (I) earthing and (II) fuse in domestic electric circuits ?
(b)
Write the name and statement of the rule used to determine the direction of the :
(I)
force experienced by a straight current-carrying conductor placed in a uniform magnetic field perpendicular to the field.
(II)
magnetic field produced around a straight conductor carrying electric current.
(ii)
Two straight current-carrying conductors (A) and (B) are shown in the figures below :
(A)
(B)(I)
Mark the direction of the magnetic fields around these current-carrying conductors (A) and (B).
(II)
Compare the strengths of magnetic fields produced
(1)
at points P and Q and ($\displaystyle 2$) at points Q and R due to these current-carrying conductors, qualitatively.
Marking-scheme solution
(i)
Live wire - Red Neutral wire - Black Earth wire - Green
(ii) 220V
(iii) (I) Earth wire provides a low resistance conducting path for current and thus, protect us from electric shock due to leakage of electric current to metallic body of electrical appliances.
(II) Fuse is a safety device which melts and breaks the electric circuit when unduly high electric current flows due to overloading and prevents damage to appliances and circuit.
(b) (i) (I)
Fleming's left-hand rule.
Stretch the thumb, fore finger and middle finger of your left hand such that they are mutually perpendicular. If the first finger points in the direction of magnetic field and second finger in the direction of current then thumb will point the direction of force acting on the conductor. (II)
Right hand thumb rule.
Imagine that you are holding a current carrying conductor in your right hand such that thumb points towards the direction of current. Then your fingers will wrap around the conductor in the direction of field lines of magnetic field.
(ii) (I)
(A)
(B)
(A)
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CBSE Class 10 Science past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.