You visited us 3 times! Enjoying our articles? Unlock Full Access!

Byju's Answer

Standard X

Physics

Resistivity

An unknown re...

Question

An unknown resistance $R_{1}$ is connected in series with a resistance of $10 Ω$ . This combination is connected to one gap of a metre bridge while a resistance $R_{2}$ is connected in the other gap. The balance
point is at $50$ cm. Now, when the $10 Ω$ resistance is removed the balance point shifts to 40 cm. The value of $R_{1}$ is (in ohms) :-

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is A 20
The null condition for a meter bridge is $\frac{R_{1}}{R_{2}} = \frac{l}{100 - l}$
for first case: $\frac{R_{1} + 10}{R_{2}} = \frac{50}{100 - 50} = 1$
or $R_{1} + 10 = R_{2} . . . (1)$
for 2nd case: $\frac{R_{1}}{R_{2}} = \frac{40}{100 - 40} = \frac{2}{3}$ or $R_{2} = 1.5 R_{1}$
now (1) becomes, $R_{1} + 10 = 1.5 R_{1}$
or $0.5 R_{1} = 10 \Rightarrow R_{1} = 20$

Suggest Corrections

Similar questions

Q. An unknown resistance

R_{1}

is connected in series with a resistance of

10 Ω

. This combination is connected to one gap of a meter bridge while a resistance

R_{2}

is connected in the other gap. The balance point is at

50 c m

. Now when the

10 Ω

resistance is removed, the balance point shifts to

40 c m

. The value of

R_{1}

is (in ohms) :

Q. In the metre bridge arrangement, an unknown resistance

R_{1}

is connected in series with resistance of

10 Ω

. When the combination is connecetd to left gap of the meter bridge and

R_{2}

is connected to right gap, balance point from left end is at

50 cm

. When

10 Ω

resistor is removed, the balance point shifts to

40 cm

. The value of

R_{1}

Q. In the metre bridge arrangement, an unknown resistance

R_{1}

is connected in series with resistance of

10 Ω

. When the combination is connecetd to left gap of the meter bridge and

R_{2}

is connected to right gap, balance point from left end is at

50 cm

. When

10 Ω

resistor is removed, the balance point shifts to

40 cm

. The value of

R_{1}

Q. An unknown resistance

R_{1}

is connected in series with resistance

10 Ω

. When the combination is connected in left gap of a metre bridge and

R_{2}

is connected in right gap, the balance point from left end is at

50 cm

. When the

10 Ω

is removed, the balance point from left end becomes

40 cm

. The value of

R_{1}

Q. Two resistances are connected in two gaps of a metre bridge. The balance point is

20

cm from the zero end. A resistance of

15 Ω

is connected in series with the smaller of the two. The null point shifts to

40

cm. The value of the smaller resistance in ohms is.

Join BYJU'S Learning Program

The correct option is A 20The null condition for a meter bridge is R1R2=l100−l for first case: R1+10R2=50100−50=1or R1+10=R2...(1)for 2nd case: R1R2=40100−40=23 or R2=1.5R1now (1) becomes, R1+10=1.5R1or 0.5R1=10⇒R1=20