mass of iron block given as

density of iron block is

now the volume of the iron piece is given as


Now when this iron block is complete submerged in oil inside the beaker the buoyancy force on the iron block will be given as

here we know that
= density of liquid = 916 kg/m^3


Now for the reading of spring balance we can say the spring force and buoyancy force on the block will counter balance the weight of the block at equilibrium



So reading of spring balance will be 16.45 N
Now for other scale which will read the normal force of the surface we can write that normal force on the container will balance weight of liquid + container and buoyancy force on block



So the other scale will read 36.47 N
Answer: R = 394.36ohm
Explanation: In a LR circuit, voltage for a resistor in function of time is given by:

ε is emf
L is indutance of inductor
R is resistance of resistor
After 4s, emf = 0.8*19, so:





R = 394.36
In this LR circuit, the resistance of the resistor is 394.36ohms.
Answer:
It should be fibre optic cable , buried underground