The stroboscopic effect is a visual phenomenon that happens when a blinking light source glows an object in movement, generating a sequence of samples. The stroboscopic effect is based on Illuminance hence it is not related to the transmission and distribution of electric power.
The resistivity of iron at 20°C is 9.71 × 108
The resistivity of silver at 20°C is 1.59 × 108
The resistivity of Glass at 20°C is 1.10 × 109
The resistivity of nichrome at 20°C is 100 × 108
Hence silver is the least resistive material in the given option.
The most common type of floodlight is the metal-halide lamp, which emits a bright white light (typically 75-100 lumens/Watt). Sodium-vapor lamps are also commonly used for sporting events because they imitate daylight conditions, and colors appear natural.
They have a very high lumen-to-watt ratio (typically 80-140 lumens/Watt), making them a cost-effective choice when certain lux levels must be provided.
The amount of flux produced by the magnet indicates the strength of the magnet. The more the magnetizing force (MMF), the more is the flux produced. The more the opposition to the flux path (i.e., reluctance or magnetic resistance) less is the flux produced. This relationship is expressed as
Flux = MMF/ Reluctance
Reluctance is the opposition offered by the material in the flux path to the establishment of the flux. The reluctance in a magnetic circuit is similar to the resistance in an electric circuit. Reluctance is the inverse of permeance.
MMF = Flux/Permeance
The steady direct current distributes itself uniformly over the whole section of a conductor but the alternating current does not distribute uniformly rather than it tends to concentrate near the surface of a conductor. In fact in the AC system, no current flows through the core and the entire current is concentric at the surface regions. This phenomenon is called skin effect.
The skin effect causes the effective resistance of the conductor to increase with the frequency of the current. The skin effect is due to eddy currents set up by the AC current. The skin effect has practical consequences in the design of radiofrequency and microwave circuits and to some extent in AC electrical power transmission and distribution systems.