Electrical engineer Interview Questions | Glassdoor

# Electrical engineer Interview Questions

"When entering an electrical engineering interview, be prepared to answer a lot of technical questions that will evaluate your problem-solving skills and fundamental understanding of engineering and physics. The precise questions you will be asked will depend heavily on the type of role you're applying for, so make sure to familiarize yourself with the company and its line of work ahead of time. To ace your interview, come ready to tackle behavioral questions your ability to excel on a team and manage difficult projects."

## Top Interview Questions

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### Innovative Leadership Project Electrical Engineer 2014 (Analog) at Lutron was asked...

Nov 21, 2013
 Q2: A pnp transistor with its base connected to a voltage source, the V source is connected to a +10V source. The emitter of the transistor is connected to a resistance, and then to the same +10V source. The collector side is connected to a capacitor, which is not charged at t=0-. Given the graph of Vsource = 10 V stepping up at t = 0 to further, draw the graph of Vout. Vout is between the point of collector and capacitor. 3 AnswersANS: Vout should be constantly -10V until t=0, and will hit V=0 V linearly from V=-10 V after t=0.Hi, Can you explain why it linearly increases? Are you assuming that Collector is tied to -10V? The pnp transistor is completely cutoff for the given biasing. The only way the capacitor is going to charge is through leakage currents. It is very slow and takes a lot of time. Please advise me if my analysis is correct.I just made it back from Lutron's HQ and I was asked for the same question. My first approach will be identifying a PNP BJT, and elaborating all 4 BJT operating regions. Before t = 0, since q = 0, by using Q = CV, we can tell that the voltage across the capacitor is 0. Hence, Vo = -10V before t = 0. Recall the capacitor's current equation: I = C*(dv/dt), we can solve for the slope of changing voltage -> dv/dt = I/C. Here, I is simply the BJT's collector current, which can be found by looking at the BJT's emitter current. Given that the (beta) parameter is infinite, we see the base current to be 0. Now, at this point, we need to look for I_E. Since the R is given to be 9.3k, and VEE = 10V, it is natural to assume V_EB = 0.7V, and thus the voltage across R = 9.3V. Therefore, I_E = 9.3/9300 = 1mA. Voila, we now values for all currents: I_E = I_C = 1mA, and I_B = 0A. Plug the I_C value into the equation: I_C/C = dv/dt (C = 1uF). We know that the slope of the voltage change is 1000V/second, or 1 Volt per millisecond. Now, we know the capacitor voltage raises at 1V/ms from -10V, but we also need to know where is the upper limit. Looking back to the BJT basics about operating regions and BJT's 2-diode model, it is not hard to identify that this PNP BJT must operate in "Saturation" region (NOT IN "ACTIVE" REGION!). The boundary of that region is V_BC <= 0.7V (I hope everybody is able to solve for this). Hence, 0.7V will be the upper limit for capacitor voltage. At this point, you will have a flat line at Vo = -10V before t = 0. and raises at 1V/ms for 10.7ms and hit Vo = 0.7V. From t = 10.7ms and on, the Vo stays at 0.7V.

### Electrical Engineer at Fitbit was asked...

Oct 13, 2013
 Draw the circuit for an active low-pass filter. 2 Answersresistor going into V- on a op amp, V+ to GND, and a resistor and cap in parallel from output to V-.There's a lot of elements to typically cover in these questions, clarifications, scoping, making sure you're answering the actual question the interviewer is looking for you to answer, etc. Could be worth doing a mock interview with one of the Prepfully Fitbit Electrical Engineer experts... they've worked in the role so they clearly know how to get through the interview. prepfully.com/practice-interviews

Apr 10, 2014

### Electrical Engineer at BD was asked...

Mar 13, 2012
 If a conveyor motor trips out, how do you diagnose it? 1 AnswerThe answer they want: You uncouple it and see if it spins freely unloaded. This only is valid for small, accessible motors, the real answer is you test the motor with a Baker analyzer and look for your standard motor defects: turn to turn shorts, open circuits, and ground faults.

### Electrical Engineer at Lutron was asked...

Mar 1, 2011
 A boat is in a swimming pool and there is a rock in the boat. What happens to the level of water if the rock is thrown out of the boat?5 AnswersIt depends on the density of the rock If the rock sinks: the water level actually falls....think about it...but this is the right answer.Stays the same (see ice melting in water physics problem; buoyancy)level of water increaseShow More ResponsesAny rock that will have the density less than water?... It will fall because due to Achimedes' Law the total bouyant force decreased, hence so it is with the volume of space occupied below the water level.It depends on the ratio of volume of the rock vs the displacement of water. This is dependent on the density of the substance. In the boat it should displace a volume of water greater than the volume of the rock since the density of the rock is greater than the density of the water. Once in the water it should displace only it's own volume which do to it's density is less than the water it had to displace while in the boat.; hence, the water level decreases.

### Electrical Hardware Design Engineer at HP Inc. was asked...

Feb 14, 2018
 Q: What does a capacitor look like at high frequency?4 AnswersA: A capacitor looks like a capacitor, inductor, and resistor in series at high frequency.An openA shortShow More ResponsesIts an short circuit at very high frequencies. Look at the impedance for a capacitor and you'll notice that the frequency is inversely related to it. (also note that capacitor impedance is purely reactive). Therefore, as frequency increases the impedance approaches 0, which acts like a short. (an inductor is the opposite)

### Electrical/Software Engineer at Sealed Air Corporation was asked...

Nov 9, 2015
 What represents P, in P=IV3 AnswersWattsPowerCurrent times voltage = power (watt)

### Electrical Engineer at Piasecki Aircraft Corp was asked...

Sep 24, 2020
 What would the current response look like if a magnet passed through a coiled wire?3 AnswersStarting at t = 0, the current would exponentially increase to a maximum, be in steady-state while the magnet is inside the coil, then exponentially decrease when the magnet leaves the coilAs soon as the magnets passes through the coil, the coil would get magnetized and as a result current would exponentially increaseFurthermore, once the magnet leaves the coil, the current would start reducing gradually.

### Electrical Engineer at TVA was asked...

Dec 7, 2011
 What is a transformer?3 AnswersObviously, it steps up or down ac voltage to decrease power loss over long distances.There are many kinds of transformers, some are 1:1 for ispolation purposes, buck, boost, buck-boost, flyback... Each has it's own area of use. To say that it steps up/down the voltage is a very limited answer and shows that you may not really understand what a transformer does or how it does it. Remember: power in = power out, so it might be a step down in voltage, but it will also be a step up in current.Transformers are used to change or convert in coming current to out going current. You can step up current fom low to high voltage or step down current from high voltage to low voltage. It depends on what you're conversion requirements are.

### Electrical Engineer at Electrolux was asked...

Aug 8, 2012
 What is your current compensation? We can not progress any further in the interview process without knowing how much you are paid! What is your current compensation?2 AnswersNo Comment!No comment
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