CameraIcon

SearchIcon

MyQuestionIcon

1

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Conduction

A 10 cm lon...

Question

A $10$ cm long copper rod is welded to $20$ cm long steel rod each having cross-section A. If their thermal conductivities are $386 J m^{- 1} s^{- 1}^{o} C^{- 1}$ and $46 J m^{- 1} s^{- 1}^{o} C^{- 1}$ the temperature of junction will be _____.
Given : Copper end is at $100^{o} C$ and steel rod end is at $0^{0} C$

A

{87.5}^{o} C

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

B

{79.3}^{o} C

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

C

75^{o} C

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

D

{71.5}^{o} C

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

Open in App

Solution

The correct option is D ${71.5}^{o} C$
$T h e t h e r m a l r e s i s t a n c e R o f r o d o f l e n g t h L,$
$a r e a o f c r o s s s e c t i o n A a n d t h e r m a l c o n d u c t i v i t y K i s g i v e n b y R = \frac{L}{K A} T h e t h e r m a l r e s i s t a n c e o f c o p p e r r o d R_{C u} = \frac{20}{386 \times A} T h e t h e r m a l r e s i s t a n c e o f s t e e l r o d R_{s t e e l} = \frac{10}{46 \times A} L e t t e m p e r a t u r e o f t h e j u n t i o n b e T C u r r e n t t h r o u g h c o p p e r r o d = C u r r e n t t h r o u g h s t e e l r o d \frac{100 - T}{R_{C u}} = \frac{T - 0}{R_{S t}} P u t t i n g t h e v a l u e s a n d s o l v i n g w e g e t T = 71.5 ℃$

Suggest Corrections

thumbs-up

0

Similar questions

Q. A cylindrical steel rod of length

0.10 m

and thermal conductivity

50 W m^{- 1} K^{- 1}

is welded end to end to copper rod of thermal conductivity

400 W m^{- 1} K^{- 1}

and of the same area of cross section but

0.20 m

long. The free end of the steel rod is maintained at

100

K and that of the copper rod at

0

K. Assuming that the rods are perfectly insulated from the surrounding, the temperature at the junction of the two rods is :

Q. Three rods of Copper, Brass and Steel were welded together to from a Y-shaped structure. Area of cross-section of each rod

= 4 {c m}^{2}

. End of copper rod is maintained at

100^{o} C

where as ends of brass and steel are kept at

0^{o} C

. Lengths of the copper, brass and steel rods are

46, 13

12 c m s

respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are

0.92, 0.26

0.12

CGS units respectively. Rate of heat flow through copper rod is:

Q. Three rods of copper, brass and steel are welded together to form a Y - shaped structure. Area of cross - section of each rod

= 4 {cm}^{2}

. End of copper rod is maintained at

100^{\circ} C

where as ends of brass and steel rods are kept at

0^{\circ} C

. Lengths of the copper, brass and steel rods are

46, 13 and 12 cm

respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are

0.92, 0.26

0.12

CGS units respectively. Rate of heat flow through copper rod is

Q. A uniform steel rod of length

50 c m

is insulated on its sides. There is a layer of water of thickness

0.2 m m

at each end of the rod. If the ends of the rod are exposed to ice of

0^{\circ} C

100^{\circ} C

. Calculate the temperature gradient in the rod. Thermal conductivities of steel and water are

0.11 c a l - c m^{- 1} s^{- 1} (^{\circ} C)^{- 1}

1.5 c a l - c m^{- 1} s^{- 1} (^{\circ} C)^{- 1}

.

Q. Figure (28-E2) shows a copper rod joined to a steel rod. The rods have equal length and equal cross sectional area. The free end of the copper rod is kept at 0°C and that of the steel rod is kept at 100°C. Find the temperature at the junction of the rods. Conductivity of copper = 390 W m⁻¹°C⁻¹ and that if steel = 46 W m⁻¹°C⁻¹.

View More

Join BYJU'S Learning Program

similar_icon

Related Videos

lock

Messengers of Heat

PHYSICS

Watch in App

explore_more_icon

Explore more

Standard VII Physics

Join BYJU'S Learning Program

CrossIcon