NIOS Class 10 Science and Technology Chapter 16: ELECTRICAL ENERGY– Chapter-wise Important Questions and Answers
NIOS Class 10 Science and Technology Chapter 16: ELECTRICAL ENERGY | MCQs, Short & Long Answer Questions | 16. ELECTRICAL ENERGY
Chapter 16: ELECTRICAL ENERGY
INTEXT QUESTIONS 16.1
1. Define the units of (i) charge (ii) electric potential.
Answer: (i) Unit of charge is Coulomb.
1C charge is the charge which when placed at a distance of 1 m from an equal like charge repels it with a of force of 9×109 N
.
(ii) Unit of potential is volt.
1 volt is the potential at a point in an electric field such that if 1C positive charge is brought from outside the field to this point against the field 1 J work is done.
2. When a glass rod is rubbed with a piece of silk it acquires +10 micro coulomb of charge. How many electrons have been transferred from glass to silk?
Answer: Here, Q=+10 μC=10×10-6 C 
and e=1.6×10-19 C 
Number of electrons
n=Qe=10×10-61.6×10-19=6.25×1013 
3. How will the force between two small electrified objects vary if the charge on each of the two particles is doubled and separation is halved?
Answer: According to Coulomb’s law ,
F=kq1q2r2 
Here, q'1=2q1 , q'2=2q2 
and r'=r2 
New force
F'=kq'1q'2r'2=k×2q1×2q2r22=4 kq1q2r²4=16×kq1q2r2=16F 
Therefore, the force becomes 16 times the original force.
4. How does the force between two small charged spheres change if their separation is doubled?
Answer: According to Coulomb’s law ,
F=kq1q2r2
Here, r'=2r 
Then the new force,
F'=kq'1q'2r'2=k×q1×q22r2= kq1q24r2=14×kq1q2r2=F4 
5. A particle carrying a charge of 1 micro coulomb (μC) is placed at a distance of 50 cm from a fixed charge where it has a potential energy of 10 J. Calculate
(i) the electric potential at the position of the particle
(ii) the value of the fixed charge.
Answer: (i) Here, U=10 
J , q=1μC=1×10-6 C 
We have,
V=Uq=101×10-6=1×107 volt 
(ii) Here, U=10 
J , q=1μC=1×10-6 C 
,r=50 cm=0.5 m
and k=9×109 Nm²C-2 
We have,
U=KQqr=10×0.59×109×1×10-6=59×103=0.56×10-3C
U=5.6×10-4 C
6. Two metallic spheres A and B mounted on two insulated stands as shown in the Fig. 16.4 are given some positive and negative charges respectively. If both the spheres are connected by a metallic wire, what will happen?
Photo Fig 16.4
Answer: Electrons will flow from sphere B to sphere A through the wire till the potentials of the two spheres become equal.
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