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Time-domain reflectometry ( reflection coefficient-resistive load)

Time-domain reflectometry or TDR is a measurement technique used to determine the characteristics of electrical lines by ... more

Current gain

In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input ... more

Open circuited stub - input impedance

In microwave and radio-frequency engineering, a stub or resonant stub is a length of transmission line or waveguide that is connected at one end only. The ... more

Voltage gain

In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input ... more

Short circuited stub - input impedance

In microwave and radio-frequency engineering, a stub or resonant stub is a length of transmission line or waveguide that is connected at one end only. The ... more

Electrical Impedance

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied. The term complex impedance may be ... more

Electrical Impedances - Phase in Series

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied. The term complex impedance may be ... more

Electrical Impedances - Phase in Parallel

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied. The term complex impedance may be ... more

Electrical Impedances - Magnitude

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied. The term complex impedance may be ... more

Current gain - simplified formula (for equal impedances)

The current gain can be calculated using current instead of power using Joule’s first law to calculate. In many cases, the input and output ... more

Voltage gain - simplified formula (for equal impedances)

The power gain can be calculated using voltage instead of power using Joule’s first law to calculate a voltage gain. In many cases, the input and ... more

Electrical Impedances - In Parallel

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied. The term complex impedance may be ... more

Electrical Impedances - In Series

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied. The term complex impedance may be ... more

Current gain (for equal impedances)

The current gain can be calculated using current instead of power using Joule’s first law to calculate. In many cases, the input and output ... more

Voltage gain (for equal impedances)

The power gain can be calculated using voltage instead of power using Joule’s first law to calculate a voltage gain. In many cases, the input and ... more

Acoustic Impedance

Acoustic impedance is the measure of the opposition that a system presents to an acoustic flow when an acoustic pressure is applied to it. Acoustic ... more

Gain of pyramidal horn antenna

A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are ... more

Optimum conical horn antenna

A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are ... more

Optimum pyramidal horn antenna - H-field

A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are ... more

Optimum pyramidal horn antenna - E-field

A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are ... more

Reflection coefficient (wave normal incidence)

At the boundary between media of different acoustic impedances, some of the wave energy is reflected and some is transmitted. The greater the difference in ... more

Ideal Transformer equation - Currents

A transformer is an electrical device that transfers energy between two circuits through electromagnetic induction. A transformer may be used as a safe and ... more

Ideal Transformer equation - Voltages

A transformer is an electrical device that transfers energy between two circuits through electromagnetic induction. A transformer may be used as a safe and ... more

Excess pressure due to water hammer

Water hammer (or, more generally, fluid hammer) is a pressure surge or wave caused when a fluid (usually a liquid but sometimes also a gas) in motion is ... more

Magnitude of Admittance in electrical circuit

In electrical engineering, admittance is a measure of how easily a circuit or device will allow a current to flow. It is defined as the inverse of ... more

Admittance - version A

Admittance is a measure of how easily a circuit or device will allow a current to flow. It is defined as the inverse of impedance. Admittance, just like ... more

Admittance (related to resistance and reactance)

In electrical engineering, admittance is a measure of how easily a circuit or device will allow a current to flow. It is defined as the inverse of ... more

Loss due to Antenna Misalignment

Antenna measurement techniques refers to the testing of antennas to ensure that the antenna meets specifications or simply to characterize it. Typical ... more

Rotary variable differential transformer(RVDT) - Rotor mechanical angle

A rotary variable differential transformer (RVDT) is a type of electrical transformer used for measuring angular ... more

Worksheet 980

PPI can be calculated from knowing the diagonal size of the screen in inches and the resolution in pixels (width and height). This can be done in two steps

Using the Pythagorean theorem, for 3 different screen resolutions:

Diagonal Resolution - Pixels

Using the Diagonal Resolution from the previous formula we calculate the PPI for 3 corresponding screen sizes :

Pixels Per Inch (PPI)

Results:

10.1 inch tablet screen of resolution 1024×600 : 117.5PPI
21.5 inch PC monitor of 1080p resolution : 102.46PPI
27 inch PC monitor of 1440p resolution : 108.78PPI

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