Advertisements
Advertisements
प्रश्न
Assume that each atom in a copper wire contributes one free electron. Estimate the number of free electrons in a copper wire of mass 6.4 g (take the atomic weight of copper to be 64 g mol−1).
Advertisements
उत्तर
Atomic weight of copper = 64 grams
No. of moles in 64 g of copper = 1
∴ No. of moles in 6.4 g of copper = 0.1
No. of atoms in 1 mole of copper = 6 × 10−23 = Avogadro's Number
No. of atoms in 0.1 mole = (6 × 10−23 × 0.1) = 6 × 1022
1 atom contributes 1 free electron.
∴ 6 × 1022 atoms contribute 6 × 1022 free electrons.
APPEARS IN
संबंधित प्रश्न
Show that if we connect the smaller and the outer sphere by a wire, the charge q on the former will always flow to the latter, independent of how large the charge Q is.
A hollow cylindrical box of length 1 m and area of cross-section 25 cm2 is placed in a three dimensional coordinate system as shown in the figure. The electric field in the region is given by `vecE = 50xhati` where E is NC−1 and x is in metres. Find
(i) Net flux through the cylinder.
(ii) Charge enclosed by the cylinder.
Can a gravitational field be added vectorially to an electric field to get a total field?
In some old texts it is mentioned that 4π lines of force originate from each unit positive charge. Comment on the statement in view of the fact that 4π is not an integer.
The electric field at the origin is along the positive x-axis. A small circle is drawn with the centre at the origin, cutting the axes at points A, B, C and D with coordinates (a, 0), (0, a), (−a, 0), (0, −a), respectively. Out of the points on the periphery of the circle, the potential is minimum at
The electric field and the electric potential at a point are E and V, respectively.
Electric potential decreases uniformly from 120 V to 80 V, as one moves on the x-axis from x = −1 cm to x = +1 cm. The electric field at the origin
(a) must be equal to 20 Vcm−1
(b) may be equal to 20 Vcm−1
(c) may be greater than 20 Vcm−1
(d) may be less than 20 Vcm−1
A particle of mass m and charge q is thrown at a speed u against a uniform electric field E. How much distance will it travel before coming to momentary rest ?
A particle of mass 1 g and charge 2.5 × 10−4 C is released from rest in an electric field of 1.2 × 10 4 N C−1. What will be the speed of the particle after travelling this distance?
A block of mass m with a charge q is placed on a smooth horizontal table and is connected to a wall through an unstressed spring of spring constant k, as shown in the figure. A horizontal electric field E, parallel to the spring, is switched on. Find the amplitude of the resulting SHM of the block. 
Consider the situation of the previous problem. A charge of −2.0 × 10−4 C is moved from point A to point B. Find the change in electrical potential energy UB − UA for the cases (a), (b) and (c).
Find the magnitude of the electric field at the point P in the configuration shown in the figure for d >> a.
The surface charge density of a thin charged disc of radius R is σ. The value of the electric field at the center of the disc is `sigma/(2∈_0)`. With respect to the field at the center, the electric field along the axis at a distance R from the center of the disc ______.
Two identical blocks are kept on a frictionless horizontal table connected by a spring of stiffness k and of original length l0. A total charge Q is distributed on the block such that maximum elongation of spring at equilibrium is equal to x. Value of Q is ______.
In general, metallic ropes are suspended on the carriers taking inflammable materials. The reason is ______.
When 1014 electrons are removed from a neutral metal sphere, the charge on the sphere becomes ______.
