10 numerical related to combination of resistor.
Answers
Q1: When three identical resistances are connected to form a triangle the resultant resistance between any two corners is 30Ω .The value of each resistance is:
90Ω54Ω
15Ω
45Ω
Answer. 45Ω. 1/RAB=1/2R+1/R=2R3=30
RAB=3R/2=3*30/2
⇒R=45Ω
Q2. Identify the changes in a circuit on adding a light bulb in parallel to the actual resistance of the circuit. It will:
decrease the total resistance
increase the total resistance
make the voltage lost in each light bulb different
make the current through each light bulb the same
not change the total current through the circuit
Answer. decrease the total resistance. For a parallel combination of two resistances,
1/Req=1/R1+1/R2
⟹Req< min {R1, the R2}
A light bulb has its own resistance and hence the total resistance of the circuit decreases when it is connected in parallel to the actual resistance of the circuit.
Q3.The least resistance that one can have from six resistors of each 0.1 ohm resistance is:
0.167 Ω
0.00167 Ω
1.67 Ω
Answer. 1.67 Ω. Least resistance is possible when all are in parallel.
⇒Req=R/6=0.16=0.0167 Ω
Question 1: The layer of the earth’s atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio wave is known as
Ionosphere
Stratosphere
Mesosphere
Exosphere
Solution: Option A. Ionosphere, The layer of the earth’s atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio wave is known as the ionosphere.
Question 2: In the following circuit, the battery E1 has an emf of 12V and zero internal resistance while the battery E has emf of 2V If the galvanometer G reads zero, then the value of the resistance X in ohm is
10
100
500
200
Solution: Option B. I1=12/(500+x), I2=2/x. As the galvanometer has zero deflection we have 12/(500+x)=2/x or x=100 ohms.
3. The normal movement of electric charges among the Earth’s surface, the various layers of the atmosphere, and especially the ionosphere, taken together, are known as :
a current conducting circuit
the global atmospheric electrical circuit
charge cloud
none of the above
Solution: Option C. The global atmospheric electrical circuit.
mark it as brainlist answer.